Steel weight calculator.
Steel weight is the cross-section area times length times density. A 20 mm carbon steel round bar weighs 2.47 kg per metre at 7.85 g/cm³. Pick the section, material and dimensions to get the mass per metre, per piece and for your quantity, with the formula shown.
Reviewed 11 Nov 2026 · Based on Section areas from nominal dimensions (geometry); Densities: ArcelorMittal Orange Book (steel), Swiss Steel 1.4301 data sheet (304), ASSDA (316), EN 1999-1-1 3.2.5 (aluminium) · Report an error
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| Size (mm) | Round bar (d) | Square bar (a) | Hex bar (across flats) |
|---|---|---|---|
| 6 | 0.222 | 0.283 | 0.245 |
| 8 | 0.395 | 0.502 | 0.435 |
| 10 | 0.617 | 0.785 | 0.680 |
| 12 | 0.888 | 1.130 | 0.979 |
| 16 | 1.578 | 2.010 | 1.740 |
| 20 | 2.466 | 3.140 | 2.719 |
| 25 | 3.853 | 4.906 | 4.249 |
| 30 | 5.549 | 7.065 | 6.118 |
| 40 | 9.865 | 12.560 | 10.877 |
| 50 | 15.413 | 19.625 | 16.996 |
| 60 | 22.195 | 28.260 | 24.474 |
| 80 | 39.458 | 50.240 | 43.509 |
| 100 | 61.654 | 78.500 | 67.983 |
| Material | Density (g/cm³) | Source |
|---|---|---|
| Carbon or alloy steel | 7.85 | ArcelorMittal Orange Book: mass per metre calculated with steel at 7,850 kg/m³ |
| Stainless 304 / 1.4301 (A2) | 7.9 | Swiss Steel Group data sheet 1.4301 (EN 10088-3): 7.90 kg/dm³ |
| Stainless 316 / 1.4401 (A4) | 8 | ASSDA, 316: the first step up: 8,027 kg/m³ typical, rounded to 8.0 |
| Aluminium alloy | 2.7 | EN 1999-1-1 clause 3.2.5: unit mass 2,700 kg/m³ (as reproduced in SCIA Eurocode training) |
Reference values, not a design.
Values are the nominal figures of the cited standards, or calculated from them where marked. The governing standard and your drawing always take precedence.
Questions buyers ask.
How do you calculate the weight of steel?
Multiply the cross-section area by the length and the density. In practical units, mass per metre in kg equals the area in mm² times the density in g/cm³, divided by 1,000. Carbon steel is taken at 7.85 g/cm³. Real bars and tubes differ slightly through rolling tolerances and corner radii.
How much does a 20 mm steel round bar weigh per metre?
About 2.47 kg per metre in carbon steel: π/4 × 20² = 314.2 mm², times 7.85 g/cm³, divided by 1,000. A 6 m length is about 14.8 kg. In stainless 316 at 8.0 g/cm³ the same bar is about 2.51 kg per metre.
How do you calculate the weight of a steel tube or pipe?
Use the ring area: π × wall × (outside diameter − wall). A 48.3 mm tube with a 4.0 mm wall has about 557 mm² of steel, so it weighs about 4.37 kg per metre at 7.85 g/cm³. Square and rectangular tubes use outer area minus inner area.
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