Punch Force Calculator
Use this punch force calculator to estimate the force required to punch a hole in materials.
Punching force4.909 US tons9,817 lb · 43.7 kN
Cut perimeter1.5708 in
Shear area0.19635 in²perimeter × thickness
Shear strength50,000 psi
Stripping force0.3682 tonsabout 7.5% of the punch force
Work done51.1 lb·ftroughly force × thickness ÷ 2
Recommended press capacity6.14 tonswith 25% margin
Minimum practical hole0.125 inpunching a hole smaller than the thickness usually breaks the punch
Hole to thickness ratio4within the usual rule
The formula
F = perimeter × thickness × shear strength
Perimeter, not area
Punching cuts around the edge of the hole, so the force depends on the perimeter times the thickness — the area of metal actually being sheared. A square hole takes more force than a round one of the same width, because 4d is larger than πd.
The rule of thumb is not to punch a hole smaller than the material is thick. Below that the punch is loaded in compression beyond what a slender tool can take, and it will snap rather than cut.