Round Bar Weight
A steel 25 mm round bar weighs about 3.85 kg/m (2.59 lb/ft). Change the size, material or length below for an exact figure.
Common round bar sizes — steel weight
| Size (mm) | kg/m | lb/ft |
|---|---|---|
| 6 mm | 0.222 | 0.149 |
| 8 mm | 0.395 | 0.265 |
| 10 mm | 0.617 | 0.414 |
| 12 mm | 0.888 | 0.597 |
| 16 mm | 1.58 | 1.06 |
| 20 mm | 2.47 | 1.66 |
| 25 mm | 3.85 | 2.59 |
| 30 mm | 5.55 | 3.73 |
| 40 mm | 9.86 | 6.63 |
| 50 mm | 15.4 | 10.4 |
| 60 mm | 22.2 | 14.9 |
| 80 mm | 39.5 | 26.5 |
| 100 mm | 61.7 | 41.4 |
Carbon steel, ρ = 7.85 g/cm³. Other materials scale linearly with density — use the selector above.
How round bar weight is calculated
Weight comes straight from geometry and density: work out the cross-section area of the profile, then multiply by length and the material's density. For round bar the cross-section follows round bar geometry, and mass per metre is that area times density. Carbon steel is 7.85 g/cm³; that single number is why a steel part weighs almost three times an identical aluminium one (2.70 g/cm³).
The quick-reference table above is calculated for carbon steel. For any other material, use the calculator's material selector — the weight scales linearly with density, so stainless (8.0) comes out about 2% heavier than steel, and aluminium about 66% lighter, for the same dimensions.
Per-metre vs. total weight
Bar, tube and section stock is usually quoted in kg per metre (or lb per foot). The calculator shows both the per-metre rate and the total for the cut length you enter — handy for working out shipping weight or checking a delivery against the packing list.
Why calculated beats a printed chart
Stock charts only list round-number sizes in one material. Real jobs use odd cut lengths, mixed materials and non-standard sections. Computing the weight from dimensions means you get the exact figure for your piece — not the nearest row on a wall chart.
References
- Densities: standard handbook values (ASM Metals Reference Book; matweb typical values). Mill stock varies a few percent with alloy and tolerance.
- Cross-section relations: standard mensuration formulas per profile geometry.
Last reviewed: 2026-07 · Calculation method & assumptions