Punch Force Calculator — Press Tonnage for Die Cutting
Calculate the punching force and minimum press tonnage for blanking, piercing or die-cutting operations — for circles, squares, rectangles or any custom perimeter, across common sheet materials.
Hole shape
mm
mm
Material
% of punch force
Punch force plus stripper force — minimum press capacity needed
- 1
Hole perimeter
π × 20 mm = 62.8 mm - 2
Punch force
62.8 × 3 × 280 ÷ 1000 = 52.78 kNPerimeter (mm) × thickness (mm) × shear strength (N/mm²) ÷ 1000 = force in kN. - 3
Stripper force
52.78 kN × 15 ÷ 100 = 7.92 kN - 4
Total press tonnage
(52.78 + 7.92) kN ÷ 9.81 = 6.19
How does this calculator work?
Punch force (kN) = Perimeter (mm) × Thickness (mm) × Shear strength (MPa) ÷ 1000. Add 10–20% for the stripper, then convert to tonnes (÷ 9.81) to get the minimum press capacity. Material shear strength is roughly 0.6–0.8 × tensile strength; select a preset or enter your own value.
Formula
How this is calculated
The blanking or punching force is the shear force the punch tip must exert to completely sever material around a closed perimeter. The standard formula is F = P × t × τ, where P is the cutting perimeter in mm, t is the sheet thickness in mm and τ is the material shear strength in N/mm² (MPa). Dividing by 1000 converts N to kN. Shear strength is typically 0.6–0.8 × the material's tensile strength; this calculator uses published mid-range values but they are editable — select "Custom" to enter your own.
The stripper force holds the sheet flat during the punch retraction stroke. It is normally 10–20% of the punch force and adds to the total tonnage the press must supply. Real operations may also need additional capacity for: die-cutting angle (shear angle on the punch face, which reduces peak force but extends stroke), worn tooling, lubrication condition and press-frame deflection. Add a minimum 20–25% safety margin beyond the calculated figure when specifying a press.
Shear strength values in this calculator are 2024 published estimates for common alloys and are marked as editable. Always verify against the specific alloy grade, temper and thickness on the material cert.
Frequently asked questions
Punch force is the theoretical shear force calculated from perimeter, thickness and shear strength. Press tonnage is the rated capacity of the machine, which must exceed the total punch + stripper force with an appropriate safety factor (typically 20–25% extra).
Only through the perimeter. A circle of diameter 20 mm (perimeter 62.8 mm) needs less force than a 20 mm square (perimeter 80 mm) of the same thickness and material, because there is less cutting edge engaging the material at once.
After the punch shears through the material, the slug tends to grip the punch as it retracts. The stripper plate exerts a force to push the sheet off the punch. Without it, the sheet would lift with the punch, misaligning subsequent hits. Stripper force is typically 10–20% of the punch force.
Also known as
TG we-Calculate Editorial Team. (2026). Punch Force Calculator — Press Tonnage for Die Cutting [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/punch-force-calculator
TG we-Calculate Editorial Team. "Punch Force Calculator — Press Tonnage for Die Cutting." TG we-Calculate. 2026. https://we-calculate.com/calculator/punch-force-calculator.
TG we-Calculate Editorial Team, "Punch Force Calculator — Press Tonnage for Die Cutting," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/punch-force-calculator
@misc{wecalculate_punch_force_calculator, title = {Punch Force Calculator — Press Tonnage for Die Cutting}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/punch-force-calculator}}, year = {2026}, note = {TG we-Calculate} }
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