Press Brake Tonnage Calculator

Inputs

Material thickness (t)

Sheet or plate thickness.

Bend length (L)

Total length of the bend line.

V-die opening (V)

Width of the lower V die. A common air-bending starting point is about 8 times material thickness.

Tensile strength (UTS)

Material ultimate tensile strength. Mild steel is commonly estimated around 400-450 MPa.

MPa

Machine margin (N)

Multiplier applied to estimated tonnage for machine selection margin.

Default result

Required press force(F_req)

324,000N

Pass

324 kN · 72,840 lbf · 33 t

Use this as a planning estimate, then confirm with the press brake and tooling manufacturer.

Estimated air-bending force with the margin multiplier applied.

Also computed

Estimated force(F)270,000N

270 kN · 60,700 lbf · 27.5 t

Air-bending force before machine margin.

Force per 1 m(F/m)270,000N

270 kN · 60,700 lbf · 27.5 t

V/t ratio(V/t)8

Die ratio is in the common air-bending range.

Common air-bending starts around V = 6t to 12t; 8t is a frequent first pass.

8t die opening(8t)24mm

Method notes 2 notes

Air-bending estimate: F = 1.6*UTS*L*t^2/V, with UTS in MPa and dimensions in mm. It is equivalent to the common 575*t_in^2/V_in tons-per-foot formula for 60 ksi mild steel.
Actual force changes with die radius, punch radius, bend angle, grain direction, tooling friction, bottoming/coining, and material batch. Do not use this as a press capacity guarantee.