Perforated sheets can be punched to a variety of different hole patterns, which change according to the size of the hole and the distance between them (the pitch). 

This article provides a guide to the different hole patterns available to you and how to calculate their open areas as a percentage. 

Types of Hole Shapes

The most popular types of hole shapes are:

Slot and rectangular holes derive from 'pulling' sheets of round or square perforated patterns.

Calculating Open Areas 

Changing the size of the holes or the pitch will result in a larger or smaller open area. 

1) Open area: round holes with a triangular pitch

Formula: 

2) Open area: round holes with a square pitch

Formula: 

3) Open area: square holes with a square pitch

Formula: 

4) Open area: square holes with a staggered pitch

Formula: 

5) Open area: slot holes with a staggered pitch

Formula: 

6) Open area: rectangular holes with a staggered pitch

Formula: 

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