Tooth pitch is defined as the number of teeth per inch (tpi). 1 inch equals 25,4 mm. In the WIKUS range, a difference is made between constant tooth pitches with uniform tooth spacing and variable tooth pitches with different tooth spacing within one toothing interval.

Variable tooth pitches are marked by two dimensions, e.g. 2-3 tpi. With this, 2 tpi signifies the maximum tooth spacing and 3 tpi signifies the minimum tooth spacing in the toothing interval.