About Metal Weight Calculator — Steel, Aluminum, Plate, Bar & Tube
The metal weight calculator turns stock dimensions into shipping and handling weight: pick the shape (plate, round/flat/square/hex bar, round or rectangular tube, or equal angle), the alloy, and the dimensions in mm or inches, and the tool computes weight = cross-section area × length × density × quantity, reported in both kilograms and pounds. Every density is pinned to an alloy-specific datasheet — carbon steel at 7,850 kg/m³ (ASTM A36), stainless 304 at the ASM Handbook 7,930 rather than the common rounded 8,000, aluminum 6061 at 2,700, through lead at 11,340 (CRC Handbook).
The section formulas are exact geometry, so the tool also guards the cases hand calculations get wrong: a tube wall that meets in the middle (ID ≤ 0), rectangular-tube walls thicker than half the smaller side, and an angle thicker than its leg are rejected rather than silently producing a negative or doubled area. Switching mm ↔ in or m ↔ ft converts the entry and clamps it into the target range, so a valid entry never turns into an error by toggling units.
How It Works
- Pick the stock shape. The dimension fields switch to the shape: plate and flat bar ask thickness × width, round bar a diameter, hex bar the across-flats distance, tubes an outside size plus wall, angle a leg plus thickness.
- Pick the alloy. The density (kg/m³) is shown in the select and used directly — the table is verified against MatWeb/ASM/CDA/CRC datasheets, cited per alloy.
- Enter dimensions in mm or inches and the length in m or ft. The unit toggle converts your entries in place (rounded to the field precision, clamped to the field caps).
- Read the results: cross-section area, weight per piece, and total weight for the quantity, in kg and lb (1 kg = 2.204623 lb). Buying by the pound? The lb figure is the one the supplier scales.
Worked Example
A fabricator needs the weight of a 1,000 × 1,000 mm sheet of 10 mm mild steel plate. Cross-section: 1,000 mm × 10 mm = 0.01 m² through the 1 m width; volume = 0.01 m² × 1 m = 0.01 m³; weight = 0.01 × 7,850 = 78.5 kg (173.06 lb) — right on the classic shop rule that 1 m² of steel plate weighs 7.85 kg per mm of thickness. Four sheets total 314 kg, which is forklift, not two-man-lift, territory.
Steel plate weight chart: kg and lb per 1 × 1 m sheet
Weight of one square metre of mild steel plate (carbon steel, 7,850 kg/m³ per the ASTM A36 datasheet) at common stock thicknesses, computed through the calculator as thickness × 1,000 mm width × 1 m length. The shop rule of thumb falls out of the density: 7.85 kg per m² per mm of thickness.
| Plate thickness | Weight (kg) | Weight (lb) |
|---|---|---|
| 3 mm | 23.55 | 51.92 |
| 5 mm | 39.25 | 86.53 |
| 6 mm | 47.10 | 103.84 |
| 10 mm | 78.50 | 173.06 |
| 12 mm | 94.20 | 207.68 |
| 20 mm | 157.00 | 346.13 |
Formulas
- Weight
W = A × L × ρ × n- Solid sections
plate/flat: A = t·w; round: A = πd²/4; square: A = a²; hex: A = (√3/2)·f²- Hollow and L sections
round tube: A = (π/4)(OD² − ID²), ID = OD − 2t; rect tube: A = wh − (w−2t)(h−2t); equal angle: A = t(2a − t)- Density table (kg/m³)
steel 7850 · SS304 7930 · Al 6061 2700 · Cu C110 8940 · brass C260 8530 · Ti Gr2 4510 · gray iron 7150 · zinc 7135 · lead 11340
Standards & References
- Densities verified against alloy-specific datasheets: MatWeb (ASTM A36 carbon steel, aluminum 6061, titanium Grade 2, gray iron ASTM A48 Class 40), ASM Handbook Vol. 1 (stainless 304, 7.93 g/cm³), Copper Development Association (C11000, C26000), CRC Handbook of Chemistry and Physics (zinc, lead)
- Exact unit factors per NIST SP 811: 1 in = 25.4 mm, 1 ft = 0.3048 m; 1 lb = 0.45359237 kg (1959 international yard-pound agreement)
- Stock-shape section formulas are exact geometry; mill tolerance on actual bar/plate weight is typically a few percent
Frequently Asked Questions
How do I calculate the weight of steel plate?
Weight = thickness × width × length × 7,850 kg/m³ (with dimensions in metres). The handy shop form: a square metre of steel plate weighs 7.85 kg per millimetre of thickness, so 10 mm plate is 78.5 kg/m² (about 16.1 lb/ft²). The chart above tabulates the common thicknesses; enter your own sheet size in the tool for exact numbers.
Why does the calculator use 7,930 kg/m³ for stainless 304 instead of 8,000?
Because 8,000 is a rounded convention, not the datasheet value: the ASM Handbook lists annealed 304 (UNS S30400) at 7.93 g/cm³ = 7,930 kg/m³. The difference is under 1%, but on a tonne of stock it is 9 kg — and this tool pins every density to a citable alloy datasheet rather than a folk figure.
How much does a 20 ft stick of 2-inch round steel bar weigh?
Switch the tool to inches/feet and enter diameter 2 in, length 20 ft: A = π/4 × (0.0508 m)² = 2.027 × 10⁻³ m², × 6.096 m × 7,850 = about 97 kg (214 lb). Quick imperial rule for round steel bar: weight (lb/ft) ≈ 2.67 × d², with d in inches — 2.67 × 4 ≈ 10.7 lb/ft, matching the tool.
What is the across-flats distance on a hex bar?
The distance between two opposite flat faces — the size a wrench grips, and the size hex stock is sold by. The section area is (√3/2) × f², about 86.6% of the enclosing square, which is why a hex bar weighs less than a square bar of the same nominal size. Do not enter the corner-to-corner width; that would overstate the weight by a third.
Why does the tool reject my tube wall thickness?
A round tube needs ID = OD − 2t > 0, and a rectangular tube needs 2t smaller than the smaller side — otherwise the "tube" has no opening and the hollow-section formula double-counts metal. If your wall really consumes the section, it is a solid bar: pick round or square/flat bar instead and the weight comes out right.
Are these weights exact enough for ordering?
The geometry and densities are exact, but mills roll to a tolerance: plate can legally run a few percent heavy, and bar/tube actual weights typically land within ±2–3% of theoretical. Suppliers price by theoretical weight for most structurals and by scale weight for others — treat the tool as the theoretical figure and allow margin when the shipment is weight-critical.