F , kN - Complete bending force required
s , mm - Material thickness
V , mm - Bending die opening
h , mm - Minimum required sheet rest length before bending
L , mm - Lenght of the bend
R , mm - internal radius
TS - Tensile strength of the metal to be bended
The present calculation is only for general purposes. If the type of material and other parameters are even slightly different the calculation can't reach industrial precision.