THREAD PITCH

In technical jargon -- thread pitch is the distance, measured parallel to the thread axis, between corresponding points on adjacent threads. Unified screws threads are designated in threads per inch, which is the number of complete threads occurring in one inch of threaded length. Thread pitch is the reciprocal of threads per inch. On an external thread, the diameter at the thread rests is the major diameter, and at its thread roots is the minor diameter. On an internal thread, it is the opposite. The diameter at the crests is the minor diameter and at the roots the major diameter.

In layman’s terms -- The thread pitch of a unified (non-metric) fastener is measured in THREADS PER INCH (TPI). You count the number of threads in an inch of threaded material. On external fasteners (like bolts), you count the ‘high points’ of the threads. On internal fasteners (like nuts) you count the ‘low points’ of the threads. Want to avoid all this tedious counting? Order our thread pitch gauge. It allows you to easily determine both the diameter and thread pitch of fasteners.

To the right, you’ll find coarse and fine thread pitches for common size fasteners. The first number represents the size of the screw, the number after the dash is the thread pitch.