Published: · Guides · ~2 min read
The weight of a steel product comes down to one rule: volume times density. Steel is 7,850 kg/m³, and every formula in the tables follows from that number. Below you can see how it applies to four common products and how to check the result.
The principle: area × length × density
For any profile, the weight per metre is the cross-section area (in m²) times 7,850 kg/m³. Take the area from the manufacturer's table or work it out from the dimensions. Example: an HEA 200 has a cross-section of about 53.8 cm², i.e. 0.005383 m². Weight per metre is 0.005383 × 7,850 = 42.26 kg/m, so a 6 m bar weighs about 253.5 kg.
Quick formulas for common products
| Product | Formula (dimensions in mm) | Example | Result |
|---|---|---|---|
| Round tube | (D − t) × t × 0.02466 | Ø48.3 × 3.2 | 3.56 kg/m |
| Sheet | thickness × 7.85 kg/m² | 3 mm | 23.55 kg/m² |
| Rebar and round bar | d² × 0.00617 | Ø12 | 0.89 kg/m |
| Square tube | (2·(B + H) − 4t) × t × 0.00785 | 40 × 40 × 2 | ≈ 2.39 kg/m |
For sheet, a 1,000 × 2,000 mm plate at 3 mm is 2 m², so 2 × 23.55 = 47.1 kg. A 6 m length of Ø12 rebar weighs 6 × 0.89 ≈ 5.3 kg.
Why the result differs slightly from the table
For a 40 × 40 × 2 square tube the simplified formula gives 2.39 kg/m, while the table shows 2.31 kg/m. The roughly 3% gap comes from the rounded corners that the formula ignores. Use the table value for orders; the formula is fine for a quick estimate or for sizes that are not in the tables.
Common mistakes
- Mixed units. The formulas above need millimetres; entering metres makes the result wrong by a factor of a thousand.
- Theoretical vs. actual weight. Rolling tolerances mean a real bar can differ by a few percent from the table value.
- Other materials. Density changes: aluminium is about 2,700 kg/m³, so steel formulas do not apply. See the density table.
- Coatings. Galvanizing and paint add weight, which matters for transport and lifting.
Use the calculator instead of formulas
If you would rather not calculate by hand, the metal weight calculator does the same operations for tubes, sheet, sections and rebar. Exact values per size are in the HEA, rebar and sheet tables, and more formulas are collected in the weight guide. Ready-calculated examples: HEA 200 and square tube 40×40×2.
Where to find these products
Once you know the weight, the next step is ordering. Below are products from the MatHaus catalogue for the sizes used in the examples, with current prices.
Links to MatHaus are affiliate links: if you buy through them, e-utilio.ro may earn a commission at no extra cost to you. Details.
Calculating a whole order?
Use the metal weight calculator for tubes, sheet, sections and rebar.