Metal Weight Calculator
Pick a shape and material, enter dimensions, get the weight in kg and lb — with nominal densities and mill-tolerance guidance.
Open calculatorLast updated: 2026-09-15
How the calculation works
- Volume comes from the standard geometry for each shape; weight is volume × nominal density.
- Densities are typical alloy values at room temperature (steel 7.85 g/cm³, aluminum 2.70, etc.).
Worked example
Interpreting the result
Weight drives shipping, structural load and material cost. Order 2% extra for mill tolerance and offcuts. The kg/m figures are also how steel is priced — knowing a 20 mm bar is 2.47 kg/m lets you sanity-check quotes instantly.
Assumptions
- Nominal densities; specific alloys vary ±1–2%.
- Prism shapes with uniform cross-section.
Limitations
- Exotic alloys, castings with draft, and machined parts need measured volumes.
- Temperature expansion affects weight only trivially.
Weight of 1 m of round bar (kg) by material and diameter
| Material | Ø 10 mm | Ø 20 mm | Ø 30 mm | Ø 50 mm |
|---|---|---|---|---|
| Carbon steel | 0.62 | 2.47 | 5.55 | 15.41 |
| Stainless steel | 0.62 | 2.48 | 5.58 | 15.51 |
| Aluminum | 0.21 | 0.85 | 1.91 | 5.30 |
| Brass | 0.67 | 2.67 | 6.01 | 16.69 |
| Copper | 0.70 | 2.82 | 6.33 | 17.59 |
Density used for each material
Worked out from the calculator's own weight and volume results.
| Material | Density (g/cm³) |
|---|---|
| Carbon steel | 7.85 |
| Stainless steel | 7.90 |
| Aluminum | 2.70 |
| Brass | 8.50 |
| Copper | 8.96 |
| Cast iron | 7.20 |
| Titanium | 4.51 |
| Lead | 11.34 |
Alloys vary. Use the density on your supplier's certificate when accuracy matters.
Worked scenario: a 20 mm steel bar, 1 m long
The calculator gives 2.466 kg (5.44 lb) for 314.2 cm³ of steel. The same bar in aluminum would weigh about a third as much, which is why aluminum is chosen where weight matters.
Mistakes to avoid
- Using one density for every grade. Stainless steels, aluminum alloys and brasses each span a range.
- Forgetting that a tube is lighter than a bar of the same outside diameter. Use the tube option with the wall thickness.
- Ignoring coatings, cut allowances and mill tolerances when you order by weight.
Frequently asked questions
How much does a steel plate weigh per m²?
Multiply thickness in mm by 7.85: a 6 mm plate is 47.1 kg/m². The rule: kg/m² = 7.85 × t(mm).
Why is aluminum so much lighter?
Density 2.70 vs steel's 7.85 — about a third. But aluminum's stiffness is also a third, so equal-stiffness parts save less weight than density suggests.