🔨 Punch Force Calculator

What this calculator does

The punch force calculator estimates the force (tonnage) a press needs to punch a hole through sheet metal, which helps in selecting an appropriately sized punch press and tooling for a job.

The formula

The standard estimate is F = P × T × S, where P is the perimeter of the hole being punched, T is the material thickness, and S is the material’s ultimate shear strength. For a round hole, perimeter is π × diameter. The result in pounds-force is also shown converted to tons (÷2000) and kilonewtons.

• Shear strength is typically about 70-80% of a material’s tensile strength and varies by alloy and temper; the values here are commonly cited approximations.
• This formula estimates the peak shearing force and does not account for stripping force, press efficiency, or dull tooling, which increase the force actually needed in practice.

This tool is for general estimating and educational purposes; consult your press manufacturer’s ratings and tooling data for production work.