Industrial Maintenance Practice Test 2026 – Complete Exam Prep Guide

Diametral pitch tells you how many teeth fit in one inch of the pitch diameter, which directly describes the size of the teeth themselves. It’s defined as the number of teeth per inch of pitch diameter (P_d = N / D), so a higher pitch means finer (smaller) teeth and a lower pitch means coarser (larger) teeth. Because it relates to how big the teeth are relative to the diameter, it’s a measure of tooth size rather than the overall gear diameter or the material. The metric counterpart to diametral pitch is module, which serves the same purpose in metric units.