Reuven — Engineering Calculation Suite
Engineering Tools
Professional calculators for facade, structural, and building performance engineering — standards-based, transparent, and free to use.
Structural
31 ToolsStructural Analyzer
Static and dynamic structural analysis with FEM, 3D visualization, and comprehensive reporting.
Wind Load Calculator
Wind pressure analysis per ASCE 7-22, Eurocode 1, and AS/NZS 1170.2.
Seismic Load Calculator
Seismic base shear, story force distribution, and design response spectrum using the Equivalent Lateral Force method.
Steel Connection Calculator
Steel connection design with bolt shear, bearing, weld capacity, block shear, and net section checks for fin plate, end plate, base plate, and bracing gusset connections.
RC Beam & Column Design
Reinforced concrete flexural and shear design with reinforcement calculation, interaction diagrams, and crack width checks.
Steel Member Design
Steel beam and column capacity checks with moment, shear, buckling, and combined interaction analysis.
Timber Design Calculator
Timber beam, column, and joist sizing with bending, shear, bearing, and deflection checks.
Load Combination Generator
Generate all factored ULS and SLS load combinations with governing case identification.
Slab Design Calculator
One-way, two-way, and flat slab design with punching shear and deflection checks.
Masonry Wall Design
Vertical and lateral load capacity with slenderness and eccentricity checks for load-bearing masonry.
Cross-Section Properties
Area, moment of inertia, and section modulus for standard steel shapes and custom sections.
Beam Deflection Calculator
Maximum deflection, bending moment, and shear force for simply supported and cantilever beams under distributed or point loads.
Beam Reactions Calculator
Support reactions, max shear, and max bending moment with SFD/BMD diagrams for single-span beams.
Column Buckling Calculator
Euler critical load, effective length, slenderness ratio, and critical stress for axially loaded columns.
Truss Analysis Calculator
Planar 2D determinate truss solver using the method of joints for member forces and support reactions.
Punching Shear Calculator
Flat-slab two-way punching shear at a column with control perimeter and capacity check per ACI 318.
Base Plate Design Calculator
AISC 360 steel column base plate: bearing area, plate size, and required thickness for concentric columns.
Continuous Beam Calculator
Multi-span beam analysis via the Three-Moment Theorem for support moments, reactions, span moments, and a bending-moment diagram.
Weld Group Calculator
Eccentrically loaded fillet welds by the elastic vector method, with shear flow, polar moment, and required fillet leg size.
Composite Beam Calculator
Steel-concrete composite beams: effective slab width, transformed section neutral axis and inertia, and plastic moment capacity.
Shear Wall Design Calculator
In-plane shear design of a reinforced-concrete structural wall per ACI 318: concrete strength Vc, horizontal reinforcement Vs, capped nominal Vn, design phi*Vn versus Vu, utilization, and minimum/required reinforcement ratios.
Prestress Losses Calculator
Itemized prestress losses for prestressed and post-tensioned concrete: elastic shortening, creep, shrinkage, and steel relaxation, the total loss in MPa and percent, and the effective prestress fpe and effective force.
Fatigue Life Calculator
S-N detail-category fatigue life and Miner cumulative damage for a variable-amplitude load spectrum: allowable cycles per block, damage sum D, predicted spectrum repeats to failure, and the constant-amplitude fatigue limit.
Snow Load Calculator (ASCE 7-22)
ASCE 7-22 roof snow loads: flat-roof load pf = 0.7 Ce Ct Is pg, the low-slope minimum load, sloped balanced load with warm- and cold-roof slope factor curves, and the leeward drift surcharge against roof projections, with results in psf and kPa.
Roof Pitch Calculator (Angle, Rafter & Area)
Roof pitch conversion between x/12, x/10, degrees and slope percent with flat-to-steep classification. Sizes common rafters from the horizontal run and pitch with an optional overhang, and converts plan footprint area to sloped roof area, roofing squares, and shingle bundles with waste.
Deck Joist Span Calculator (IRC R507.6)
Maximum residential deck joist spans from 2021 IRC Table R507.6 (40 psf live + 10 psf dead, No. 2 grade): southern pine, Douglas fir-larch/hem-fir/SPF, and redwood/cedar 2x6 to 2x12 joists at 12, 16, or 24 inches on center, with the quarter-span cantilever check and a reverse lookup of every adequate size-and-spacing combination.
Deck Beam Span & Footing Size Calculator (IRC R507.5)
Maximum multi-ply deck beam spans from 2021 IRC Table R507.5(1) for southern pine, Douglas fir-larch/hem-fir/SPF, and redwood/cedar build-ups of (2) 2x8 to (3) 2x12, with the joist span rounded up to the next table column. Sizes the post footing from the tributary load at 40 psf live + 10 psf dead against 1500-3000 psf soil bearing presets, and converts sonotube piers to concrete volume with 60-lb and 80-lb bag counts.
Wall Framing Calculator (Studs, Plates & Headers)
Lumber takeoff for a conventionally framed stud wall per IRC 2021 R602 conventions: layout studs at 16 or 24 inches on center plus two extras per corner, one per T-intersection, and two kings, two jacks, and a cripple row per opening. Totals single or double top plate lineal footage, two-member header stock with 3-inch bearing each side, 4x8 sheathing sheets at 10% waste, and an advisory framing-nail weight — quantity counting only, not structural design.
Board Foot Calculator (Lumber BF & Cost)
Board feet and lumber cost from a multi-item list using the trade formula BF = nominal thickness x nominal width x length / 12 — nominal dimensions by convention, so a 2x6 counts as 2 x 6 despite dressing to 1.5 x 5.5 actual. Hardwood quarters thickness shortcut (4/4 = 1 in through 8/4 = 2 in), per-piece and per-line BF, running totals with a priced-BF subtotal, cost from optional dollars-per-board-foot prices on each line, and a display-only nominal-versus-actual dressed-size reference table.
Deck Ledger Fastener Calculator (IRC R507.9)
Required 1/2-inch lag screw and thru-bolt on-center spacing from 2021 IRC Table R507.9.1.3(1) for a deck ledger fastened to a 2-inch nominal solid-sawn band joist, with the joist span rounded up to the governing column, staggered two-row fastener counts along the ledger run, Figure R507.9.1.3(2) placement reminders, and a reverse lookup of the largest joist span an existing fastener spacing supports.
Header Span Calculator (IRC R602.7)
Maximum allowable spans and jack stud counts from 2021 IRC Table R602.7(1) for 2- and 3-ply built-up 2x6 to 2x12 headers in exterior bearing walls supporting a roof and ceiling at 30 psf ground snow, with building-width columns of 12, 24, and 36 ft, the NJ = 1 framing-anchor allowance, and a reverse lookup listing every tabulated header adequate for a required opening span with utilization.
Concrete & Foundations
11 ToolsFoundation Design
Shallow foundation design with bearing capacity, settlement analysis, punching shear, and flexural reinforcement per ACI 318, Eurocode 7, and AS 2159.
Concrete Mix Design
Mix proportioning per ACI 211 with w/c ratio, aggregate sizing, and SCM replacement calculations.
Pile Foundation Design
Axial capacity and settlement analysis using alpha, beta, and SPT methods for driven and bored piles.
Rebar Scheduling & Detailing
Bar bending schedules and cutting length calculation with shape code library for reinforcement detailing.
Concrete Crack Width Calculator
Flexural crack width wk of reinforced concrete with crack spacing and limit check per Eurocode 2.
Development Length Calculator
Rebar development length, Class A/B tension lap splices, and compression development per ACI 318-19.
Anchor Bolt Design Calculator
Single cast-in anchor tension and shear strengths with governing failure mode per ACI 318-19 Ch.17.
Rebar Weight Calculator
Reinforcement steel mass from a bar schedule with totals by size in kilograms and tonnes.
Concrete Volume Calculator
Concrete quantity for slabs, footings, columns, and beams with bag count and cement/sand/aggregate breakdown.
Brick, Block & Mortar Calculator
How many bricks or concrete blocks a wall needs from its dimensions and openings, using published rates for US modular, queen, king and UK standard brick and 8/6/4 in CMU or custom unit sizes. Includes premixed mortar bags, masonry sand quantity, and pallet counts with a waste allowance.
Concrete Steps Calculator (Volume & Riser Layout)
Solid poured-concrete steps takeoff from the total rise: equal-riser layout rounded up against the IRC R311.7.5 7.75-inch maximum riser with a 10-inch minimum tread check, stepped-mass volume of width x riser x tread x n(n+1)/2 plus an optional full-height top landing, a 10% waste allowance with cubic-foot and cubic-yard totals, 60-lb (0.45 ft³) and 80-lb (0.60 ft³) premixed bag counts, and formwork quantities as riser board lineal feet plus the two stepped side profiles in square feet.
Geotechnical
12 ToolsRetaining Wall Calculator
Retaining wall design with Rankine/Coulomb earth pressure, overturning/sliding/bearing stability checks, and reinforcement design for gravity and cantilever walls.
Soil Classification
Automatic USCS and AASHTO classification with Casagrande plasticity chart and grain-size analysis.
Bearing Capacity Calculator
Ultimate, gross, and net allowable bearing capacity of shallow footings (Terzaghi/Meyerhof).
Consolidation Settlement Calculator
Primary consolidation settlement of clay for NC and OC soils using Terzaghi theory.
Soil Compaction Calculator
Field dry density, relative compaction, air voids, and saturation against a Proctor maximum per ASTM D698.
Seepage Flow Calculator
Darcy law and flow-net seepage: hydraulic gradient, velocity, and discharge through soil masses.
Lateral Earth Pressure Calculator
Rankine active and passive earth pressure and thrust on retaining walls with surcharge and water table.
Slope Stability Calculator
Infinite-slope factor of safety for cohesionless, c-phi, and seepage cases.
Cantilever Sheet Pile Wall
Simplified cantilever sheet pile embedment depth in cohesionless soil using Rankine active and passive coefficients and a net-pressure moment balance about the toe: theoretical depth d0, design depth D = 1.2-1.3 d0, and the maximum bending moment.
Soil Liquefaction Triggering
Simplified Seed-Idriss / NCEER liquefaction-triggering analysis: cyclic stress ratio CSR, cyclic resistance ratio CRR7.5 from corrected SPT (N1)60, magnitude scaling factor and the factor of safety against liquefaction with a verdict.
Mononobe-Okabe Seismic Earth Pressure
Pseudo-static seismic active earth pressure on a retaining wall by the Mononobe-Okabe method: seismic inertia angle, coefficient KAE, static KA, total seismic thrust PAE, the Seed-Whitman dynamic increment and the point of application.
Retaining Wall Block Calculator (SRW ≤ 4 ft)
Segmental retaining wall block takeoff for simple gravity walls up to 4 ft of exposed height per NCMA-style practice: courses and blocks per course from standard 12x4x9, large 18x6x12, or custom block sizes with the buried base course included (the greater of 6 in or 10% of the exposed height), optional cap units one per block width of length, compacted leveling-pad gravel 6 in deep by the block depth plus 12 in wide with a 1.15 loose-to-compacted factor, and the 12-in clean drainage-rock column over the exposed height — taller, surcharged, or sloped-backfill walls are referred to the engineered retaining-wall calculator.
Hydraulics & Water
18 ToolsPlumbing & Drainage Sizing
Pipe sizing via fixture unit method with flow rate, velocity, and self-cleansing velocity checks.
Pump Sizing Calculator
System curve generation, duty point selection, and NPSH verification with affinity law calculations.
Stormwater Drainage Calculator
Rational method pipe and channel sizing with IDF curves and runoff coefficient analysis.
Rainwater Harvesting Calculator
Roof catchment yield (V = A·R·C·eff) and tank sizing with a month-by-month water balance.
Detention Basin Calculator
Stormwater detention storage via the Modified Rational Method with critical-duration search.
Water Hammer Calculator
Joukowsky pressure surge, wave celerity and critical period 2L/a for rapid and gradual valve closure.
Open-Channel Flow Calculator
Manning's equation uniform flow for rectangular, trapezoidal, triangular, and circular channels.
Weir & Notch Flow Calculator
Discharge for rectangular, V-notch, and Cipolletti thin-plate weirs per ISO 1438.
Culvert Sizing Calculator
Inlet and outlet control capacity for circular and box culverts per FHWA HDS-5.
Hydraulic Jump Calculator
Hydraulic jump in a rectangular channel: upstream Froude number, sequent (conjugate) depth, downstream velocity and Froude number, specific-energy loss, percentage dissipated, jump length and the USBR jump classification.
Evapotranspiration (ET0) Calculator
Reference crop evapotranspiration by the Hargreaves equation (FAO-56 alternative): extraterrestrial radiation from latitude and day-of-year, crop ET via the crop coefficient Kc, and the net irrigation requirement with monthly totals.
Gravity Sewer Design Calculator
Circular gravity sewer design with Manning's equation: full-flow capacity and velocity, proportional depth d/D at the design flow, partial-flow velocity, capacity utilization and a self-cleansing velocity check.
Rational Method Peak Runoff Calculator
Peak stormwater runoff by the rational method Q = CiA with an area-weighted composite runoff coefficient, time of concentration by the Kirpich and FAA formulas, and SCS/NRCS Curve Number runoff depth and volume, with peak flow in m³/s, cfs and L/s.
Gutter & Downspout Sizing Calculator
K-style gutter sizing and downspout counts from representative SMACNA-style practice capacities: roof plan area adjusted by pitch factors from 1.0 (flat to 3/12) to 1.3 (12/12), normalized to the 1 in/hr capacity basis with the local 5-minute 10-year rainfall intensity, 5-in (2,500 ft²) and 6-in (3,840 ft²) K-style adequacy with utilization and a smallest-adequate recommendation, and per-type counts of 2x3, 3x4, and 4-in round downspouts from both drainage capacity and the 40-ft advisory spacing.
Septic Drain Field Size Calculator
Septic drain field (leach field) sizing from representative published state tables with the local health department always governing: design flow at 150 gpd per bedroom (Maryland COMAR 26.04.02.05 residential minimum; NY allows 110 gpd/bedroom with post-1994 fixtures), application rate from the NY Appendix 75-A Table 4B percolation bands transcribed cell-for-cell (1.20 gal/ft²/day at 1–5 min/in stepping down to 0.45 at 46–60 min/in), required trench-bottom area as flow ÷ rate, total absorption trench length at a 2- or 3-ft width split into equal laterals of at most 100 ft, minimum septic tank guidance from NY Table 3 (1,000 gal through 3 bedrooms, 1,250 at 4, 1,500 at 5), unsuitable-soil guidance toward mound and alternative systems for perc rates faster than 1 or slower than 60 min/in, and a required-area chart across every perc band at the chosen bedroom count.
Water Softener Sizing Calculator (Grains)
Softener grain-capacity sizing from representative plumbing-trade practice: household demand at 75 gal per person per day, hardness in grains per gallon or ppm converted at 17.1 ppm/gpg, dissolved clear-water iron compensated at +5 gpg per 1 ppm (published guides commonly cite 4–5; iron above ~0.3 ppm often wants dedicated treatment ahead of the softener), the weekly grain load on a one-regeneration-per-week basis matched to the smallest fitting standard capacity from 24,000 to 80,000 grains, a utilization chart across all six sizes against the 100% line, and twin-tank or frequent-regeneration guidance when even the largest single-tank size is too small — all framed as estimates to confirm against the manufacturer’s sizing chart.
French Drain Calculator (Gravel, Fabric & Pipe)
French drain material estimator from representative drainage-trade practice: trench volume from width (6/9/12-in presets or 6–24-in custom), depth, and run length with the standard 4-inch perforated pipe displacement subtracted so stone the pipe already fills is not bought, washed drainage gravel in cubic feet, cubic yards, and tons at 1.4 tons per cubic yard (link to gravel-aggregate for other materials), non-woven filter fabric from the burrito-wrap girth — twice the width plus twice the depth plus a 12-inch lap, covering walls, bottom, and a full top pass — counted in 3 × 100 ft rolls at 90% overlap-effective coverage, perforated pipe with a 5% fittings allowance rounded up to 10-ft sticks, a slope check against the 1% practice minimum (0.12 in/ft, with the 0.5% smooth-wall nuance in prose) or the required fall when no drop is entered, and a gravel-tons-by-width comparison chart.
Sprinkler Zone Calculator (GPM & Zones)
Irrigation zone calculator from representative trade practice: available flow measured with a bucket-test helper (gallons ÷ seconds × 60, with a use-this button) or typical meter-size presets (12/16/25 GPM for 5/8-, 3/4-, and 1-inch meters, clearly labeled typical — measure yours), a 90% design margin on the measured supply so a hot-afternoon pressure dip does not starve the farthest heads, sprinkler-head rows by type (label, GPM each from the nozzle chart, count) summed into total demand, the zone count as total demand divided by usable flow rounded up per the Hunter design-handbook method, an advisory equal demand split, a per-head-type maximum-heads-per-zone fit table (epsilon-guarded floor), and a demand-per-zone bar chart against the budget line.
Transportation & Surveying
10 ToolsFlexible Pavement Design Calculator
AASHTO 1993 structural number from ESALs, reliability, serviceability, and subgrade MR.
Vertical Curve Calculator
Parabolic crest and sag curves: A, K, BVC/EVC, high/low point, and sight-distance length per AASHTO.
Stopping Sight Distance Calculator
AASHTO reaction, braking, and total stopping sight distance with grade correction (US & SI).
Horizontal Curve Calculator
Simple highway circular curve: minimum radius from design speed, plus tangent, curve length, external, middle ordinate, long chord, degree of curve, and PC/PT stationing.
Rigid Pavement Design Calculator
AASHTO 1993 PCC slab thickness from ESALs, reliability, concrete strength, subgrade k, load transfer J, and drainage Cd.
Traffic Flow Capacity Calculator
Greenshields uninterrupted flow: capacity q_max = vf·kj/4, optimum speed and density, and free-flow vs congested branches with a flow-density curve.
Area by Coordinates Calculator
Area of a closed traverse or land parcel from vertex coordinates using the Shoelace formula, plus perimeter, centroid, and winding direction.
Traverse Closure & Bowditch Adjustment
Latitudes, departures, linear misclosure, and relative precision of a closed traverse, balanced with the Bowditch compass-rule adjustment.
Bearing & Distance (COGO) Calculator
Inverse and forward COGO computations: distance and azimuth between coordinates, and a new point from bearing and distance.
Asphalt Tonnage Calculator
Tons of hot-mix asphalt from up to five paved areas, compacted thickness, and mix density. Includes HMA, binder, and open-graded density presets, waste factor, 25-ton truckloads, and an optional cost estimate.
Mechanical & Machine Design
10 ToolsPressure Vessel Thickness Calculator
Wall thickness for cylindrical and spherical shells under internal pressure per ASME BPVC Section VIII Div 1, with corrosion allowance and MAWP.
Bolt Torque & Preload Calculator
Tightening torque and preload via T = K·F·d with ISO metric thread geometry and ISO 898-1 property classes.
Pipe Thermal Expansion Calculator
Linear thermal growth, restrained thermal stress, anchor force, and expansion-loop leg length for process and power piping.
Orifice Flow Meter Calculator
Volumetric and mass flow through a thin-plate orifice per ISO 5167, with diameter ratio, velocity-of-approach factor, pipe and throat velocities, and throat Reynolds number.
Tank Volume Calculator
Partial-fill liquid volume for vertical, horizontal, and rectangular tanks, with total capacity, percent full, and ullage in cubic metres, litres, and US gallons.
Reynolds Number & Friction Factor
Pipe-flow Reynolds number, laminar/transitional/turbulent regime, and Darcy friction factor via 64/Re or Colebrook-White and Swamee-Jain, with relative roughness and a Moody curve.
Shaft Design Calculator
Required solid circular shaft diameter under combined bending and torsion by the maximum-shear (Tresca) or distortion-energy (von Mises) theory, with fatigue stress-concentration factors and actual bending, shear and von Mises stresses.
Helical Spring Calculator
Helical compression spring design: spring index, Wahl correction factor, spring rate k = G·d⁴/(8·D³·Na), deflection, Wahl-corrected shear stress and solid length, with manufacturability warnings on spring index.
Bearing Life Calculator
Rolling-element bearing fatigue life per ISO 281: equivalent dynamic load, basic rating life L10 = (C/P)^p in million revolutions and hours for ball and roller bearings, plus reliability-adjusted life.
Vibration Isolation Calculator
Machine vibration isolator selection: natural frequency from static deflection or spring stiffness and mass, frequency ratio, damped transmissibility, and isolation efficiency, with a reverse mode giving the required static deflection for a target isolation percentage.
Marine & Coastal
3 ToolsWave Load Calculator (Morison)
Maximum wave force on a vertical cylindrical pile via the Morison equation and linear Airy wave theory: velocity, acceleration, inertia and drag force, total force and overturning moment.
Metacentric Height Calculator
Floating box-barge stability: displacement, KB, BM, metacentric height GM = KB + BM - KG, stability verdict, and righting arm GZ at a chosen heel.
Breakwater Armor Unit Calculator
Hudson formula armor unit weight for rubble-mound breakwaters: relative density, equivalent cube size, layer thickness, and units per area with a Kd armor-type table.
Building Physics & Energy
11 ToolsEnergy Efficiency Calculator
Building thermal performance, energy consumption analysis, and cost savings projections.
Thermal Movement Calculator
Thermal expansion, joint widths, and sealant selection for facade elements.
Condensation Risk Calculator
Interstitial condensation analysis using the Glaser method with vapour pressure profiles.
Thermal Bridge Calculator
Thermal junction analysis with psi-values, temperature factors, and standards compliance.
Heat Loss & Gain Calculator
Room-by-room heating and cooling load analysis with fabric loss, ventilation, solar gains, and internal gains.
U-Value Calculator
Assembly thermal transmittance with layer-by-layer resistance calculation and thermal bridging corrections.
Overheating Risk Assessment
Summer comfort analysis with hourly simulation per CIBSE TM59/TM52, EN 15251, and ASHRAE 55.
Moisture & Mould Risk Calculator
Surface temperature factor and mould growth prediction for wall junctions and assemblies.
Psychrometric Calculator
Moist-air properties: humidity ratio, enthalpy, dew point, and wet-bulb at any atmospheric pressure.
Degree Days & Energy Calculator
Heating and cooling degree-days with a simplified building energy estimate per ASHRAE & CIBSE.
Insulation R-Value Calculator (IECC Climate Zones)
Prescriptive minimum insulation R-values from IECC 2021 Table R402.1.3 for ceilings, wood-frame walls, floors, basement walls, and crawl space walls across climate zones 1-8, with the full compound code option text (cavity and continuous-insulation alternatives), a fiberglass batt purchase plan with layers and bag counts, and blown-in fiberglass or cellulose depth in whole inches.
HVAC & Comfort
17 ToolsDaylight / Solar Gain
Solar heat gain, visible light transmittance, daylight factor, and shading analysis for glazing systems.
Pipe & Duct Sizing
Pipe and duct sizing calculator using Darcy-Weisbach equation with pressure drop, fitting losses, and material databases.
HVAC Load Calculator
Heating and cooling load sizing with sensible/latent analysis, psychrometrics, and equipment tonnage.
Ventilation Rate Calculator
Required airflow calculation per ASHRAE 62.1, EN 16798, and CIBSE Guide B with demand-controlled ventilation.
Heat Exchanger LMTD Calculator
LMTD and effectiveness-NTU sizing/rating for counter-flow and parallel-flow heat exchangers.
Fan & Pump Affinity Laws Calculator
Affinity laws for new flow, pressure, and power from speed or impeller diameter changes.
Cooling Tower Calculator
Range, approach, heat rejection, evaporation, blowdown, and makeup water with thermal efficiency.
Heat Pump COP Calculator
Carnot and actual COP, EER, running cost, and savings versus electric resistance heating.
Expansion Tank Sizing Calculator
Hydronic expansion tank sizing by the ASHRAE closed-loop method: water expansion volume, acceptance factor, and required tank volume.
Chilled & Hot Water Flow Calculator
Hydronic chilled-water and hot-water flow rate from a cooling or heating load via Q = m·cp·ΔT: mass flow, L/s, m³/h and US GPM, plus pipe velocity and a suggested pipe size for a target velocity.
Air Mixing Calculator
Adiabatic mixing of two moist-air streams such as outdoor and return air: mass-weighted mixed dry-bulb, humidity ratio, enthalpy, relative humidity and dew point on a dry-air basis.
Cooling Coil Load Calculator
Cooling coil total load split into sensible and latent components from the entering and leaving air conditions using ASHRAE psychrometrics, with dry-air mass flow, cooling in kW and refrigeration tons, the sensible heat ratio (SHR), and the condensate removal rate.
Geothermal Borehole (GSHP) Sizing Calculator
Ground-source heat pump vertical borehole sizing: ground load from the building heating or cooling load and COP, total bore length from the W/m heat-transfer rate, and the number and depth of boreholes per ASHRAE / IGSHPA rule-of-thumb design.
Gas Pipe Sizing Calculator (NFPA 54)
Low-pressure natural gas pipe sizing by the NFPA 54 / IFGC longest-length method: BTU/hr load (or a per-appliance list) to CFH demand, Schedule 40 capacities from Table 402.4(2) at the rounded-up run length, the smallest adequate size with utilization and next size up, and a Spitzglass formula cross-check.
Attic Ventilation Calculator (IRC 1/150 & 1/300 Rule)
Required attic net free ventilating area per IRC 2021 R806.2: 1/150 of the attic floor area, or 1/300 when both exception conditions are met (Climate Zone 6-8 ceiling vapor retarder, 40-50% of the NFA in upper-portion ventilators), split 50/50 into upper exhaust and eave intake targets. Converts each half into ridge vent lineal feet, 8x16 soffit vents, continuous soffit strip, box vents, gable louvers, or turbines from representative NFA ratings, and a check mode grades an existing vent mix with pass/fail, deficit, and an intake/exhaust balance warning.
Water Heater Sizing Calculator (FHR & Tankless GPM)
Water heater sizing both ways the DOE Energy Saver method recommends: tank mode fills in the DOE Worksheet for Estimating Peak Hour Demand/First Hour Rating with the published averages — shower 20 gal per use, shaving 2, hand dishwashing or food prep 3, automatic dishwasher 7, clothes washer 25 (top-loader) or 15 (H-axis) — and matches the total to a storage or heat-pump model with a first hour rating at or just above the demand (size by the EnergyGuide FHR, never by tank volume); tankless mode sums representative simultaneous fixture flows (shower 2.0 gpm, kitchen sink 1.5, lavatory 1.0, clothes washer 2.0, dishwasher 1.5) and computes the required temperature rise from groundwater (regional presets 40-70 °F) to the fixed 120 °F delivery, compared against a typical gas unit of about 5 gpm — and an electric unit of about 2 gpm — at a 70 °F rise.
Whole House Fan Sizing Calculator (CFM & Attic NFA)
Whole house fan sizing from published DOE and manufacturer practice: target airflow at 2, 2.5, or 3 CFM per square foot of living area (the QuietCool good/better/best sizing ladder, inside the PNNL Building America 1.5–3 CFM/ft² band), an air-changes-per-hour cross-check from house volume against the 12–23 ACH effective range with a tall-ceiling size-up flag, the attic exhaust net free area the fan needs at 1 ft² per 750 CFM in ft² and in² (doubled to gross area for screened or louvered vents, with a link to attic-ventilation for vent selection), the open-window guideline of 4 ft² per 1,000 CFM, and a good/better/best CFM comparison chart — windows-open night-flush ventilation cooling, not a substitute for load-based HVAC design.
Electrical & MEP
19 ToolsElectrical Load Calculator
NEC Article 220 demand factor calculations with service sizing, cable selection, and panel schedule generation.
Lighting Design Calculator
Luminaire layout using zonal cavity method with lux levels, uniformity ratio, and power density.
Solar PV Yield Calculator
Panel array sizing and annual energy yield estimation with tilt and azimuth optimisation.
Cable Tray & Conduit Sizing
Fill ratio and derating calculations for cable trays, conduits, and electrical raceways.
Voltage Drop Calculator
Single and three-phase conductor voltage drop with NEC 3%/5% and IEC 60364 compliance checks.
Fault Current Calculator
Available short-circuit current at a transformer and downstream points via the point-to-point method.
Transformer Sizing Calculator
Required kVA, next standard rating, and full-load currents for single and three-phase transformers.
Power Factor Correction Calculator
Capacitor kVAR sizing, current and loss reduction, and demand-charge savings for PF correction.
Grounding Resistance Calculator
Earthing resistance of driven rods, parallel rods, and ground grids against the 25-ohm NEC target.
Generator Sizing Calculator
Standby/prime genset kW and kVA from running load and motor starting with derating and spare margin.
Arc-Flash Calculator
IEEE 1584 arcing current, incident energy, arc-flash boundary, and NFPA 70E PPE category.
Motor Starting & Voltage Dip Calculator
Three-phase motor full-load and locked-rotor current, bus voltage dip, and reduced-voltage starting method comparison.
Lightning Protection (Rolling Sphere)
Rolling-sphere method of IEC 62305-3 for sphere radius, protected radius and area, mesh size, and protection angle.
EV Charging Load Calculator
Electric-vehicle charging (EVSE) load sizing per NEC Article 625: per-charger continuous load at 125%, single- and three-phase circuit current, total connected demand in amps and kVA, and an energy-management diversity factor for the recommended feeder/service ampacity.
Harmonic Distortion & K-Factor Calculator
Total harmonic distortion (THD), true RMS and transformer K-factor from a measured harmonic spectrum per IEEE 519 and IEEE C57.110, with the recommended K-rated transformer and distortion-limit guidance.
Conductor Ampacity Calculator (NEC 310.16)
NEC Table 310.16 wire sizing for copper and aluminum conductors: ampacity by insulation temperature rating with ambient-temperature correction and conductor-bundling adjustment, continuous-load 125% sizing, and termination temperature limit checks.
Conduit Bending Calculator (Offset, Saddle, Stub-Up)
EMT hand-bender layout for the three everyday bends: two-bend offsets with the exact 1/sin(angle) multiplier and shrink, 3-point saddle center and outer marks, and 90 degree stub-ups using the bender take-up deduct per trade size, with mark positions from the obstruction and a bend-spacing check.
Box Fill Calculator (NEC 314.16)
Minimum outlet, device, and junction box volume per NEC 314.16(B): Table 314.16(B) allowances for conductors by AWG size, internal clamps, support fittings, device yokes at two allowances each, and equipment grounding conductors, with every standard box that fits listed with its utilization percentage.
Outlet Spacing Calculator (NEC 210.52)
Minimum dwelling-unit receptacle counts per NEC 210.52, verified against the published 2023 code text (every encoded value is identical in the 2020 edition): wall spaces entered in feet under the 210.52(A) 6-ft rule — no point along the floor line more than 6 ft from a receptacle, so receptacles at most 12 ft apart, with any space 2 ft or wider counting and doorways, fireplaces, and fixed cabinets breaking the wall line — and wall countertop segments entered in inches under the 210.52(C) 24-in rule with the 12-in minimum width, each list giving per-segment minimums plus wall, countertop, and grand totals, documented as code minimums that real layouts exceed, with the 2023 island/peninsula change (receptacles now optional with a future-provision requirement) and GFCI/AFCI protection covered in prose.
Renewable Energy
4 ToolsWind Turbine Power Calculator
Swept area, available wind power, electrical output, Betz-limit fraction, and annual energy production with a power curve.
Hydroelectric Power Calculator
Net head, hydraulic and electrical power, and annual energy from flow rate, gross head, penstock losses, and efficiency.
Battery Storage Sizing Calculator
Battery bank sizing for off-grid and backup systems: usable and nominal capacity, series/parallel count, and C-rate.
Solar Water Heating Calculator
Flat-plate solar thermal collector sizing and output via the Hottel-Whillier equation: useful energy gain Qu, instantaneous efficiency, daily hot-water energy, required collector area and solar fraction.
Acoustics
2 ToolsAcoustic Calculator
Sound transmission, absorption, and acoustic properties for glass, concrete, and composite materials.
Reverberation Time Calculator (RT60)
Room reverberation time RT60 by the Sabine (0.161 V / A) and Eyring formulas from room volume, surface areas and absorption coefficients, with total absorption in sabins, mean absorption coefficient, and an assessment against a target RT for the intended room use.
Fire & Life Safety
6 ToolsFire Resistance Rating
Fire resistance rating calculator with REI classification for concrete, steel, and timber structural members.
Fire Sprinkler Design
Hydraulic calculation with head layout, pipe sizing, and water supply analysis for sprinkler systems.
Occupant Load & Egress Calculator
Occupant load, required egress width, and number of exits per IBC 1004, 1005, 1006.
Needed Fire Flow Calculator
Needed fire flow (NFF) by the ISO / AWWA area method NFF = 18 x C x sqrt(A): construction-class coefficient, effective floor area, required flow in gpm and L/min, the required flow duration and the total water supply for hydrant and storage sizing.
Egress Window Calculator (IRC R310)
Emergency escape and rescue opening sizing and checking per IRC 2021 R310.2 (source-verified): size-it mode returns the net clear width or height needed to reach the 5.7 sq ft net clear opening — 5.0 sq ft for grade floor or below grade openings per the R310.2.1 exception — floored at the 24-in height and 20-in width minimums with the governing rule named, check-it mode grades an as-built opening rule by rule (area, width, height, and the R310.2.2 44-in maximum sill) with the margin and IRC section on each badge, and a window well card checks the R310.2.3 minimums (9 sq ft horizontal area with projection and width each at least 36 in) and flags the permanently affixed ladder or steps R310.2.3.1 requires for wells deeper than 44 in.
Smoke & CO Detector Calculator (IRC R314/R315)
Minimum smoke and carbon monoxide alarm counts for a dwelling unit per the IRC 2021 published text (source-verified): smoke alarms per R314.3 — one in each sleeping room, one outside each separate sleeping area in the immediate vicinity of the bedrooms, and one on each additional story including basements and habitable attics but not crawl spaces or uninhabitable attics — and CO alarms per R315.2.1/R315.3 where the dwelling has a fuel-fired appliance or an attached garage with a communicating opening: one outside each sleeping area plus one inside any bedroom with a fuel-burning appliance in the room or its attached bathroom, every count itemized as per-rule breakdown lines with section references, documented as conservative planning minimums with the placement restrictions (3 ft from tub/shower bathroom doors, 6–20 ft from cooking appliances by sensor type), interconnection (R314.4/R315.5), and hardwired-plus-battery power rules (R314.6/R315.6) covered in prose.
Site & Sustainability
22 ToolsWindow Fabrication Calculator
Cutting lists and fabrication drawings for aluminum windows with optimized material usage.
Embodied Carbon Calculator
Whole-life carbon emissions with lifecycle assessment across stages A1-D per EN 15978.
Temporary Works Design
Scaffolding, formwork, and shoring load checks with stability analysis for construction.
Earthwork Cut & Fill Calculator
Cut and fill volumes by average-end-area and prismoidal methods with shrinkage and haul balance.
Life-Cycle Cost Calculator
LCCA with NPV, simple and discounted payback, and savings-to-investment ratio for two options.
Stair Calculator (Rise, Run & Code Check)
Straight-flight stair design from the floor-to-floor rise: number of risers, actual riser height, treads, total run, stair angle and stringer length, checked against IBC, IRC, OSHA or custom riser and tread limits and the Blondel 2R + T comfort rules.
Rigging Sling Load Calculator
Lifting sling tension per leg from load weight, leg count and sling angle from horizontal, with the angle factor, required WLL per leg for vertical, choker and basket hitches, horizontal compression on the load, and OSHA / ASME B30.9 sling-angle warnings.
Gravel & Aggregate Calculator
Cubic yards, cubic metres, and tonnage of crushed stone, pea gravel, sand, crusher run, riprap, or topsoil from rectangular, circular, or direct areas. Compaction and waste allowances with bag counts and 10 yd³ truckloads.
ADA Ramp Slope Calculator
Accessible ramp design per the 2010 ADA Standards and ICC A117.1: required run at 1:12, 1:16 or 1:20 (plus the 1:10 and 1:8 existing-site exceptions), intermediate landings from the 30 in rise limit, total footprint, handrail flag, and a check mode that grades an existing rise and run with pass/fail margins.
Decking Board & Fastener Calculator
Deck board and fastener quantities from the footprint: rows from the board width plus gap (5.5 in and 3.5 in presets or custom), lineal footage with a 10% straight or 15% diagonal waste allowance, boards to buy at 8 to 20 ft stock lengths, and face screws at two per joist crossing or hidden clips at one per crossing plus a starter per row, with 100/350/1750-count box suggestions.
Baluster Spacing Calculator (IRC 4-Inch Rule)
Guard baluster layout under the IRC R312.1.3 4-inch-sphere rule: the minimum number of balusters for a clear opening between posts, the perfectly even clear gap with a pass/fail badge, and center-line layout marks measured from the post face, plus an as-built check mode that verifies an existing baluster count and reports the margin to the 4-inch limit or a custom maximum such as the 4-3/8-inch allowance for guards on the open sides of stairs.
Drywall Calculator (Sheets, Mud, Tape & Screws)
Drywall quantity takeoff for a rectangular room (with or without the ceiling) or a list of wall segments, subtracting door and window openings. Counts 4x8, 4x10, or 4x12 sheets at 10% standard or 15% complex waste and converts representative trade coverage rates into joint compound pounds and 4.5-gallon buckets, tape lineal feet and 500-ft rolls, screws and 1000-count boxes, plus 8-ft corner bead sticks from the entered outside-corner footage.
Tile Calculator (Tiles, Thinset & Grout)
Tile quantity takeoff for a floor or wall entered directly in square feet or as length by width: tiles and boxes from the effective footprint of each tile including its grout joint, with pattern waste at 10% straight or offset, 15% diagonal, and 20% herringbone. Counts 50-lb thinset bags from representative 1/4, 3/8, or 1/2 inch square-notch trowel coverage and grout pounds from the industry-standard joint-geometry formula, rounded into 10-lb and 25-lb bags.
Fence Calculator (Posts, Rails, Pickets & Concrete)
Wood fence material takeoff from the run length: posts and sections at 6 or 8 ft on center, rails per section by style (3 privacy, 2 picket, 2-3 post-and-rail), pickets from the picket width and gap, post length to buy rounded to even-foot stock from the trade 1/3-height bury rule (2 ft minimum), post holes at three times the post width over a 4-inch gravel base, and concrete per hole and total with 60-lb and 80-lb premix bag counts plus one extra post and hardware set per gate.
Paver Patio Calculator (Pavers, Base & Sand)
Interlocking concrete paver takeoff for patios, walkways, and driveway aprons: pavers to buy from 4x8, 6x6, 6x9, 12x12, or custom face sizes with pattern waste (5% running or stack bond, 10% herringbone, 15% circular), compacted aggregate base at 4-in pedestrian or 8-in vehicular depth with a 1.15 loose-to-compacted factor, bedding sand at the fixed 1-inch ICPI screed, polymeric jointing sand bags at representative 80 ft² coverage, and 8-ft edge restraint sticks along the open perimeter.
Siding Calculator (Squares, Planks & Trim)
Horizontal lap-siding takeoff from up to 20 wall elevations with door and window openings subtracted: siding squares and course-equivalent lineal feet at trade-practice exposures (8.25-in plank at 7-in exposure, 6.25-in at 5-in, or a custom 3-12 in) with 10% simple or 15% complex waste, 12-ft or 16-ft plank counts, housewrap rolls figured on the gross area because the wrap runs behind the opening flanges, starter strip along the wall bases, and 10-ft corner trim sticks from the corner count and height.
Trench Excavation Calculator (OSHA Slopes & Spoil)
Trench excavation takeoff with sides at the OSHA maximum allowable slope from 29 CFR 1926 Subpart P, Appendix B, Table B-1 (excavations under 20 ft): stable rock vertical, Type A 3/4:1, Type B 1:1, Type C 1.5:1 by the competent-person soil classification, top width at grade and trapezoidal cross-section, bank volume in cubic yards, loose spoil from representative swell presets (15% rock, 30% Type A, 25% Type B, 12% Type C) or a custom 0-60% override, 10-yd³ truckloads, and the two Subpart P safety flags: protective system required at 5 ft or deeper per 1926.652(a)(1) with the stable-rock exception, and egress within 25 ft of lateral travel at 4 ft or deeper per 1926.651(c)(2).
Baseboard & Trim Calculator
Baseboard and trim takeoff for up to 20 rooms: installed lineal feet per room as the rectangular perimeter minus the standard 3-ft deduction per door opening (floored at zero for door-heavy closets, never negative), a 10% waste allowance for miters, copes, and splices, whole-stick purchase counts for 8-, 12-, and 16-ft stock, painter's caulk at one tube per 40 lineal feet of the INSTALLED length because waste offcuts are never caulked, and inside/outside corner counts echoed with the finish-carpentry joinery advisories — cope the inside corners so joints stay tight through seasonal movement, miter the outside corners at 45 degrees.
Flooring Calculator (Boxes, Waste & Underlayment)
Plank and laminate flooring takeoff: net floor area from up to 20 rooms minus up to 20 exclusions (kitchen islands, hearths, built-ins), boxes to buy from the coverage printed on the product carton (default 22 ft² — representative only) with a waste allowance keyed to the installation layout (10% straight, 15% diagonal, 20% herringbone/parquet), underlayment counted as 100-ft² rolls on the net area without the layout waste, an optional cost estimate from a price per box, and a chart comparing the box count across all three layouts.
Grading & Drainage Slope Calculator (IRC R401.3)
Foundation drainage grade check per the IRC 2021 published text (source-verified): the ground surface must fall not fewer than 6 in within the first 10 ft of the foundation (R401.3, a 5% equivalent), impervious surfaces within 10 ft of the foundation sloped not less than 2% away from the building per the R401.3 Exception, and drains or swales where lot lines, walls, slopes, or other physical barriers prohibit the fall — pass/fail verdict with the margin in inches and the governing section reference, the required fall for any run at the governing rate with a first-10-ft caveat for longer runs and the swale/drain note for shorter ones, plus a slope converter between percent, inches per foot, and 1:N ratio with exact round-trips (5% = 0.6 in/ft = 1:20, 2% = 0.24 in/ft = 1:50).
Sod & Grass Seed Calculator
Lawn establishment estimator with sod and seed modes: sod mode converts lawn area into standard 2 ft × 5 ft (10 ft²) rolls with a 5% or 10% cutting-waste allowance and into pallets at your supplier's stated coverage (300–700 ft² input, 450 default — pallet coverage varies by supplier, so it is asked, not assumed); seed mode computes pounds of grass seed from rates verified against University of Tennessee Extension W160-B "Turfgrass Establishment: Seeding" (table midpoints: Kentucky bluegrass 1.75, tall fescue 6.5, perennial ryegrass 5, hulled bermudagrass 0.75 lb per 1,000 ft²) at full rate for a new lawn or half rate for overseeding an existing thin stand, both modes adding starter-fertilizer bags at a representative 5,000 ft² per bag sized on the bare ground area rather than the waste-adjusted sod order, with the reminder that rates vary by cultivar and region — follow your seed bag and local extension.
Dumpster Size Calculator (Volume & Weight)
Roll-off container sizing from a list of demolition projects: representative debris factors for roof tear-off by squares and shingle layers (1/3 yd³ + 240 lb per square per layer — the encoded 240 lb is the midpoint of the published 230–250 lb/square trade range for 3-tab, architectural runs heavier), drywall (0.2 yd³ + 220 lb) and flooring (1/3 yd³ + 150 lb) per 100 ft², deck removal (1 yd³ + 300 lb per 100 ft²), kitchen (3 yd³ + 1,500 lb) and bath (1.5 yd³ + 800 lb) demo per room, plus custom per-unit debris, with loose volume at a 15% fluff factor and weight never fluffed, checked against 10/20/30/40 yd³ containers with representative 1–4 ton rental weight allowances — one size step up when weight alone overflows, split-load guidance when heavy debris like shingles governs by weight, and a chart of the load against every container allowance, all framed as estimates to confirm with your hauler (overage fees and prohibited items vary).