Press brake tonnage chart by thickness
A quick-reference table of air-bending force per foot for the thicknesses shops actually run, using the standard 575 × t² ÷ V relation with the 8× V-opening rule. Multiply by your bend length in feet, then add margin — and read the caveats below the table before you buy against it.
The chart (air bending, mild steel)
| Thickness | V-opening (8×t) | Tons per foot | Stainless (×1.5) | Aluminium (×0.5) | 4 ft bend | 8 ft bend | 12 ft bend |
|---|---|---|---|---|---|---|---|
| 1.5 mm · 1/16" (0.0625) | 1/2" | 4.5 | 6.8 | 2.3 | 18 | 36 | 54 |
| 2 mm · 5/64" (0.078) | 5/8" | 7.0 | 10.5 | 3.5 | 28 | 56 | 84 |
| 2.5 mm · 3/32" (0.094) | 3/4" | 10.1 | 15.1 | 5.0 | 40 | 81 | 121 |
| 3 mm · 1/8" (0.125) | 1" | 9.0 | 13.5 | 4.5 | 36 | 72 | 108 |
| 4 mm · 5/32" (0.156) | 1-1/4" | 14.1 | 21.1 | 7.0 | 56 | 113 | 169 |
| 4.5 mm · 3/16" (0.1875) | 1-1/2" | 13.5 | 20.3 | 6.8 | 54 | 108 | 162 |
| 5 mm · 13/64" (0.203) | 1-5/8" | 16.4 | 24.6 | 8.2 | 66 | 131 | 197 |
| 6 mm · 1/4" (0.25) | 2" | 18.0 | 27.0 | 9.0 | 72 | 144 | 216 |
| 8 mm · 5/16" (0.3125) | 2-1/2" | 22.5 | 33.8 | 11.3 | 90 | 180 | 270 |
| 10 mm · 3/8" (0.375) | 3" | 27.0 | 40.5 | 13.5 | 108 | 216 | 324 |
| 12 mm · 1/2" (0.5) | 4" | 35.9 | 53.8 | 17.9 | 144 | 287 | 431 |
| 14 mm · 9/16" (0.5625) | 4-1/2" | 40.3 | 60.4 | 20.1 | 161 | 322 | 484 |
| 16 mm · 5/8" (0.625) | 5" | 44.9 | 67.3 | 22.4 | 180 | 359 | 539 |
| 18 mm · 3/4" (0.75) | 6" | 53.9 | 80.8 | 26.9 | 216 | 431 | 647 |
| 20 mm · 13/16" (0.8125) | 6-1/2" | 58.5 | 87.8 | 29.3 | 234 | 468 | 702 |
| 22 mm · 7/8" (0.875) | 7" | 62.7 | 94.1 | 31.4 | 251 | 502 | 752 |
| 25 mm · 1" (1.0) | 8" | 71.9 | 107.9 | 36.0 | 288 | 575 | 863 |
How to use it
- Find your worst row: the thickest material you bend, not the most common. The heavy job happens a few times a year and sizes the machine.
- Take the tons-per-foot figure for your alloy — mild steel column, stainless column, or aluminium column.
- Multiply by your bend length in feet. Force is per unit length: double the bend length and you double the tonnage at the same material and tooling.
- Add margin — 20% is a planning allowance for alloy temper, tooling condition and V-opening reality.
- Check the bend method. Bottoming needs several times the air-bend figure and coining more again — the bend method guide covers the multipliers.
What this chart assumes
- Air bending — the lowest-force method. Bottoming and coining are multiples of these figures, not increments.
- V = 8 × thickness — the common starting point for mild steel. A smaller V raises the force and tightens the radius; a larger V lowers the force and opens it.
- Mild steel baseline — stainless at about 1.5× and aluminium at about 0.5×, planning ratios rather than alloy data.
- Your actual tooling — the tooling maker's chart overrides any table, including this one.
What the chart cannot tell you
Whether the machine can make the part at all. Bed length, throat depth, daylight and stroke fail more parts than tonnage — the size guide and the machine selector cover the four numbers that decide. The tonnage guide works through the calculation in full, and the gauge chart converts gauge numbers into the thicknesses this table needs.
Send us your worst row
Thickness, bend length and alloy — we will come back with a machine configuration sized to the heavy job, not the average one.