Steel weight calculator
Weight of plate, flat and square bar from three dimensions; round bar, hexagon and tube are covered by the formulas below. Results in kilograms, pounds and kg per metre.
Formulas (carbon steel, density 7.85)
| Section | Formula | Example |
|---|---|---|
| Plate / sheet | kg = t × w × l × 7.85 / 10⁶ ; kg/m² = 7.85 × t | 10 × 1500 × 3000 → 353.3 kg; 10 mm = 78.5 kg/m² |
| Flat / square bar | kg/m = t × w × 0.00785 | 50 × 10 → 3.93 kg/m; 50 square → 19.6 kg/m |
| Round bar | kg/m = D² × 0.006165 | Ø 50 → 15.4 kg/m; Ø 100 → 61.7 kg/m |
| Hexagon bar | kg/m = AF² × 0.006798 (AF = across flats) | AF 36 → 8.81 kg/m |
| Round tube / pipe | kg/m = (D − t) × t × 0.02466 | 114.3 × 6.02 → 16.1 kg/m; 48.3 × 3.2 → 3.56 kg/m |
| Square hollow section | kg/m ≈ (4 × a − 4 × t − 2×(4−π)×r_ext… ) simplified: kg/m ≈ 0.0314 × t × (a − t) (sharp-corner approx.; EN 10219 tables give exact) | 100 × 100 × 5 → ≈ 14.9 kg/m (table: 14.7) |
| Angle (equal) | kg/m ≈ 0.00785 × t × (2a − t) | 50 × 50 × 5 → 3.73 kg/m (table: 3.77) |
Plate weight per square metre
| t mm | kg/m² | t mm | kg/m² | t mm | kg/m² |
|---|---|---|---|---|---|
| 0.5 | 3.93 | 0.7 | 5.50 | 1 | 7.85 |
| 1.5 | 11.78 | 2 | 15.70 | 2.5 | 19.63 |
| 3 | 23.55 | 4 | 31.40 | 5 | 39.25 |
| 6 | 47.10 | 8 | 62.80 | 10 | 78.50 |
| 12 | 94.20 | 15 | 117.75 | 20 | 157.00 |
| 25 | 196.25 | 30 | 235.50 | 40 | 314.00 |
| 50 | 392.50 | 60 | 471.00 | 80 | 628.00 |
| 100 | 785.00 | 120 | 942.00 | 150 | 1,177.50 |
Frequently asked questions
How do you calculate the weight of a steel plate?
Weight (kg) = thickness (mm) × width (mm) × length (mm) × density (g/cm³) ÷ 1,000,000. For carbon steel (7.85) a 10 × 1500 × 3000 mm plate weighs 353 kg; per square metre a 10 mm plate is 78.5 kg.
What is the density of steel?
Carbon and low-alloy steel 7.85 g/cm³ (some standards use 7.80 or 7.87); austenitic stainless 7.9–8.0; ferritic/martensitic stainless 7.7; duplex 7.8; tool steel 7.7–7.85; bearing steel 7.81. Use the standard's nominal density for weight-based invoicing (EN 10079: 7.85 for structural steel).
How do you calculate round bar weight per metre?
kg/m = D² (mm) × 0.006165 for carbon steel (D in mm). A 50 mm round is 15.4 kg/m; 100 mm is 61.7 kg/m. For stainless multiply by 1.02 (8.0/7.85).
How do you calculate steel tube weight?
kg/m = (D − t) × t × 0.02466 for carbon steel, with outside diameter D and wall t in mm. A 114.3 × 6.02 mm pipe (NPS 4 Sch 40) is 16.1 kg/m.
Nominal densities per EN 10079 / EN 10088-1 / ASTM A240 Annex; commercial weights may use 7.80 or 7.87 by agreement.