Press Brake Tonnage Calculator
Estimate press brake tonnage per foot for air bending from thickness, V-die opening, and material strength.
Using this calculator responsibly
The Press Brake Tonnage calculator is an engineering aid for checking a shop-floor estimate before a setup, quote, or process review. Enter values in the units shown, confirm material properties against the applicable specification, and keep a record of the assumptions used. Calculator output does not override machine capacity, tooling limits, part requirements, or a qualified engineer's approval.
Before using a result in production, repeat the calculation with the extreme values allowed by the print or process window. Check that the selected material, thickness, geometry, and safety factor reflect the actual job. If a result approaches a press, die, fastener, or machine limit, stop and verify it with the equipment manufacturer or responsible engineer.
Inputs and results
Read every field label before entering data and avoid mixing inch and metric values. A useful result should be traceable to the job number, revision, material certification, and machine or tooling record. Treat warnings, invalid ranges, and unusual outputs as reasons to inspect the inputs rather than as values to work around.
Air bending tonnage depends mostly on the die opening (the V-width), the material thickness, and the material strength. Wider V-dies need dramatically less force but give a larger minimum radius.
The result is force per unit length of bend — multiply by the bend length to get total tonnage, then confirm it is within the brake’s rating.
Formula: Tons/ft ≈ (575 × T²) / V (mild steel; scale by material factor)
Worked example
- Bend 0.125 in mild steel in a 1.0 in V-die: Tons/ft ≈ 575 × 0.125² / 1.0 = 9.0 tons/ft.
- A 4 ft bend therefore needs about 36 tons.
Frequently asked questions
How is press brake tonnage calculated?
Air-bend tonnage per foot ≈ (575 × thickness² ÷ V-die width) scaled by material factor. Widen the V-die to lower tonnage.