Steel round bar weight calculator
A Ø10 steel round bar weighs 0.617 kg/m, Ø20 2.466, Ø30 5.549 and Ø50 15.41 kg/m. A table of 34 diameters from 6 to 200 mm with the 6 m bar weight, a separate square bar table and a calculator for any size.
Short answer
Steel round bar weighs 0.006165 · d² kg/m (π/4 · d² · 7.85 / 1000, d in mm), square bar 0.00785 · a². A Ø20 bar is 2.466 kg/m, a 6 m length 14.8 kg; Ø40 is 9.865 kg/m; 20 mm square 3.14 kg/m. The diameter table is below.
Steel round bar weight: 6–200 mm table
Dimensions and tolerances of hot-rolled round bar are set by EN 10060; small diameters are also sold bright drawn. The mass is worked out from the nominal size for carbon and structural steel — S235, S355, EN8/C45 and 4140/42CrMo4 all weigh 7.85 g/cm³:
| Diameter, mm | Cross-section, mm² | kg/m | 6 m bar, kg | Metres per tonne |
|---|---|---|---|---|
| 6 | 28 | 0.222 | 1.3 | 4 505 |
| 8 | 50 | 0.395 | 2.4 | 2 534 |
| 10 | 79 | 0.617 | 3.7 | 1 622 |
| 12 | 113 | 0.888 | 5.3 | 1 126 |
| 14 | 154 | 1.208 | 7.3 | 827.5 |
| 16 | 201 | 1.578 | 9.5 | 633.6 |
| 18 | 254 | 1.998 | 12.0 | 500.6 |
| 20 | 314 | 2.466 | 14.8 | 405.5 |
| 22 | 380 | 2.984 | 17.9 | 335.1 |
| 25 | 491 | 3.853 | 23.1 | 259.5 |
| 28 | 616 | 4.834 | 29.0 | 206.9 |
| 30 | 707 | 5.549 | 33.3 | 180.2 |
| 32 | 804 | 6.313 | 37.9 | 158.4 |
| 35 | 962 | 7.553 | 45.3 | 132.4 |
| 36 | 1 018 | 7.990 | 47.9 | 125.2 |
| 40 | 1 257 | 9.865 | 59.2 | 101.4 |
| 45 | 1 590 | 12.48 | 74.9 | 80.1 |
| 50 | 1 963 | 15.41 | 92.5 | 64.9 |
| 55 | 2 376 | 18.65 | 111.9 | 53.6 |
| 60 | 2 827 | 22.20 | 133.2 | 45.1 |
| 65 | 3 318 | 26.05 | 156.3 | 38.4 |
| 70 | 3 848 | 30.21 | 181.3 | 33.1 |
| 75 | 4 418 | 34.68 | 208.1 | 28.8 |
| 80 | 5 027 | 39.46 | 236.8 | 25.3 |
| 90 | 6 362 | 49.94 | 299.6 | 20.0 |
| 100 | 7 854 | 61.65 | 369.9 | 16.2 |
| 110 | 9 503 | 74.60 | 447.6 | 13.4 |
| 120 | 11 310 | 88.78 | 532.7 | 11.3 |
| 130 | 13 273 | 104.19 | 625.2 | 9.6 |
| 140 | 15 394 | 120.84 | 725.0 | 8.3 |
| 150 | 17 671 | 138.72 | 832.3 | 7.2 |
| 160 | 20 106 | 157.83 | 947.0 | 6.3 |
| 180 | 25 447 | 199.76 | 1 198.5 | 5.0 |
| 200 | 31 416 | 246.62 | 1 479.7 | 4.1 |
Mass grows with the square of the diameter: Ø40 weighs four times as much as Ø20 (9.86 against 2.47 kg/m), Ø100 twenty-five times. The last column helps when you buy bar by the tonne.
Square bar: EN 10059 table
A square of side a has an area of a², so a metre weighs a² · 0.00785 kg. That is 27 % more than a round bar of the same size (4/π = 1.27): 20 mm square is 3.14 kg/m, Ø20 round 2.466 kg/m.
| Side, mm | Cross-section, mm² | kg/m | 6 m bar, kg | Metres per tonne |
|---|---|---|---|---|
| 6 | 36 | 0.283 | 1.7 | 3 539 |
| 8 | 64 | 0.502 | 3.0 | 1 990 |
| 10 | 100 | 0.785 | 4.7 | 1 274 |
| 12 | 144 | 1.130 | 6.8 | 884.6 |
| 14 | 196 | 1.539 | 9.2 | 649.9 |
| 16 | 256 | 2.010 | 12.1 | 497.6 |
| 18 | 324 | 2.543 | 15.3 | 393.2 |
| 20 | 400 | 3.140 | 18.8 | 318.5 |
| 22 | 484 | 3.799 | 22.8 | 263.2 |
| 25 | 625 | 4.906 | 29.4 | 203.8 |
| 28 | 784 | 6.154 | 36.9 | 162.5 |
| 30 | 900 | 7.065 | 42.4 | 141.5 |
| 32 | 1 024 | 8.038 | 48.2 | 124.4 |
| 35 | 1 225 | 9.616 | 57.7 | 104.0 |
| 40 | 1 600 | 12.56 | 75.4 | 79.6 |
| 45 | 2 025 | 15.90 | 95.4 | 62.9 |
| 50 | 2 500 | 19.63 | 117.8 | 51.0 |
| 60 | 3 600 | 28.26 | 169.6 | 35.4 |
| 70 | 4 900 | 38.47 | 230.8 | 26.0 |
| 80 | 6 400 | 50.24 | 301.4 | 19.9 |
| 90 | 8 100 | 63.59 | 381.5 | 15.7 |
| 100 | 10 000 | 78.50 | 471.0 | 12.7 |
In the calculator choose “Square bar” and enter the side. Hot-rolled square has slightly rounded corners, so the real mass is a touch below the table.
Where the numbers come from
The area of a circle is π·d²/4; for Ø20 that is 314.2 mm². Times 7.85 g/cm³ and divided by 1000 gives 2.466 kg/m. Hence the shortcut 0.006165 · d² — the same one used for the nominal mass of rebar (rebar weight calculator).
The same Ø20 bar weighs 2.482 kg/m in 304 stainless and 0.848 kg/m in aluminium. Hot-rolled bar has a diameter tolerance both ways, so a delivery can weigh a few per cent more or less than the table. In lb/ft: kg/m × 0.672.
The same bar in another material
Stainless round bar (304 and 316L), aluminium round bar, rebar with a metres-per-tonne table. Flat bar, plate, tube and sections — steel weight calculator.
Frequently asked questions
How much does a 20 mm steel round bar weigh?
2.466 kg/m; a 6 m length 14.8 kg. Ø16 weighs 1.578 kg/m, Ø25 3.853 kg/m.
What is the formula for round bar weight?
m = π/4 · d² · 7.85 / 1000 = 0.006165 · d² kg/m, with d in mm. For Ø50: 0.006165 · 2500 = 15.41 kg/m.
How much does 20×20 square bar weigh?
3.14 kg/m (20 · 20 · 7.85 / 1000); a 6 m length 18.8 kg. 30 mm square is 7.065 kg/m.
How much does a 100 mm steel round bar weigh?
61.65 kg/m, so 370 kg per 6 m length. A 10 mm thick disc cut from it weighs 0.62 kg.
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