Bending force calculator
How many tons does that bend need? Enter sheet thickness, bend length and die opening — the required press brake force follows from the material's tensile strength.
How bending force is calculated
For air bending, the standard rule of thumb is F (kN/m) = (K × Rm × S²) / V — with K a die-geometry constant (1.42 here, sources range 1.3–1.6), Rm the material's tensile strength, S the sheet thickness and V the die opening. Multiply by the bend length for the total force; divide kN by 9.81 for the metric tons shown on every press brake gauge. Note the S²: doubling the thickness quadruples the force — that's why thick plate needs such heavy machines.
What V-opening should I choose?
The everyday rule is V = 8 × thickness (this calculator suggests exactly that when you leave the field empty). A wider V lowers the required force but makes a larger inside radius and needs a bigger flange; a narrower V does the opposite.
Does this apply to bottoming or coining too?
No — this formula is for air bending, by far the most common method. Bottoming needs roughly 3–5× more force and coining far more still; use your tooling supplier's tables for those.
Are these values safe to use directly?
Treat the result as an estimate with margin: real force varies with die radius, friction, material batch and bend direction versus rolling direction. Never plan a bend at 100% of your machine's capacity — and mind the maximum force per metre of your tooling as well.
Is my data sent anywhere?
No — this runs entirely in your browser with plain JavaScript. Nothing is uploaded.
