Enter the outside radius of the die into the calculator to determine the ideal die opening size.

Die Opening Formula

The following equation is used to calculate the Die Opening.

D = OR * .07071 * 4

  • Where D is the die opening diameter (in)
  • OR is the outside radius of the die (in)

What is a Die Opening?


A die opening is the size of the die used to cut or punch a pattern in sheet metal. When designing a custom stamp, it’s essential to know this dimension to estimate cost and delivery time accurately.

Trying to guess at the size of a custom die opening isn’t an effective way to design a stamp.

The reason it is called a die opening is because of the fact that it is the opening between the dies (tools). The die opening is usually determined by what size of a material you are cutting.

For example, a die opening that cuts a 2”x 2”x 2” piece will have three dies (2” x 2” x 2” each) and they would be stacked on top of each other so that they make up the whole length of your material. This way when it gets cut out of the material, you will have a stack of three individual pieces. In this way it’s like cutting three times at one time with one press stroke