Structural Calculators
31 free structural calculators — standards-based, with formulas, worked examples, and no sign-up.
Structural design runs in a fixed order: establish the loads, combine them, then check members and connections against a design code. The tools here follow that order. Wind, seismic, and snow loads come from ASCE 7-22 (with Eurocode 1 and AS/NZS 1170 alternatives in the wind tool), the load combination generator assembles the factored ULS and SLS cases per Eurocode 0 or ASCE 7 LRFD/ASD and flags the governing one, and the member design tools then check steel per EC3/AISC 360, reinforced concrete per Eurocode 2/ACI 318, timber per EC5/NDS, and masonry per EC6/TMS 402.
Pick the tool by how far into design you are. For a quick statics answer — reactions, shear and moment diagrams, a deflection number — the beam reactions, beam deflection, and continuous beam calculators get you there in seconds without touching a code. When a member has to pass, move to the code tools: steel member design for LTB and interaction checks, RC design for reinforcement, column buckling for Euler slenderness. The structural analyzer sits at the top for indeterminate frames and trusses that hand methods will not cover. Connections get their own tools — steel connection (bolts, welds, block shear), weld group, base plate per AISC 360 — because member capacity means nothing if the joint fails first.
A separate cluster serves residential wood construction directly from the IRC prescriptive tables: deck joist spans from Table R507.6, deck beams and footings from R507.5, ledger fastening from R507.9, and window/door headers from R602.7. Those tables are the code — if your deck or wall fits the table's assumptions, no engineering calculation is required, and the calculators tell you when you have stepped outside them.
All Structural Tools
Structural 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.
Frequently Asked Questions
Should I start with the load calculators or the member design tools?
Loads first, always. A steel beam check is meaningless with a guessed load. Run wind, snow, or seismic as your project requires, feed the results through the load combination generator to find the governing factored case, and only then size members. The one exception is early scheming, where the beam deflection tool with a rough UDL gives a fast sanity-check span-to-depth.
When is the deck joist span table enough, and when do I need timber design?
The IRC R507.6 table covers standard residential decks — 40 psf live / 10 psf dead, the listed species and grades, joists at 12/16/24 in. centers. Stay inside those assumptions and the table is the code-approved answer. Hot tubs, roof loads, unusual species, or spans past the table mean engineered design: that is the timber design calculator, which applies the EC5/NDS adjustment factors explicitly.
What is the difference between the beam deflection tool and the structural analyzer?
The beam deflection and beam reactions tools use closed-form formulas for single-span determinate beams — instant and transparent. The continuous beam tool extends to multi-span via the three-moment theorem. The structural analyzer is a full FEM engine for frames and trusses where those hand methods break down. Use the smallest tool that models your structure; the answers are easier to verify.