Thread TPI to pitch (mm) converter

Convert threads per inch to pitch in mm and back.

Calculating…

How it's calculated

Pitch [mm] = 25.4 ÷ TPI

Some imperial and metric threads are almost identical in pitch (for example 1/4"-20 UNC at 1.27 mm and 1.25 mm metric) but will cross-thread or strip. Always confirm with a thread gauge and by measuring the diameter.