What the Punching Force Calculator does
This tool gives the force a punch press needs to pierce a hole or cut a shape in sheet metal, so you can size the press and tooling. Enter the cut perimeter, the sheet thickness and the material, and it returns the punch force in tonnes and kN, plus the stripping force. It is built for fabricators punching holes and cutouts in panels, brackets and enclosures.
The result is the standard shear calculation, force equals perimeter times thickness times shear strength. It runs entirely in your browser and updates as you type.
How to use it
- Enter the cut perimeter in millimetres (π × diameter for a round hole, 2 × (length + width) for a rectangle).
- Enter the sheet thickness.
- Choose the material.
- Read the punching force in tonnes and kN, plus the stripping force.
Why use it here
It is free, instant and private, with no sign-up. Working from the cut perimeter keeps it universal: round holes, rectangles, slots and any profile use the same input, and you get punch force and stripping force together for sizing the press.
Tip: to plan the bends on the same part use the bend allowance and press brake tonnage calculators, and to weigh the sheet use the metal weight calculator.
Frequently asked questions
- How is punching force calculated?
- Punch force = cut perimeter × sheet thickness × material shear strength. The tool divides by 9810 to give tonnes. For a round hole the perimeter is π × diameter; for a rectangle it is 2 × (length + width); for a slot add the two straight sides and the two half-circle ends.
- What is the cut perimeter for my hole?
- It is the length of the cut edge. Round Ø10 hole: π × 10 ≈ 31.4 mm. A 20 × 30 mm rectangle: 2 × (20 + 30) = 100 mm. Enter that perimeter value and the tool does the rest.
- What is stripping force?
- After punching, the sheet grips the punch and a stripping force is needed to pull it back out. It is roughly 10 to 20 percent of the punch force; the tool shows about 15 percent as a guide. Heavier or oily material can need more.
- Which shear strength does it use?
- Each material option applies a typical shear strength: mild steel about 350, stainless about 520, aluminium about 170, copper about 200 and brass about 280 N/mm². Shear strength is roughly 0.8 of tensile strength.
Related metal & sheet metal
Last updated: June 23, 2026