⚙️ Diametral Pitch Calculator
Calculate a gear’s diametral pitch and related dimensions from the number of teeth and pitch diameter.
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What diametral pitch is
Diametral pitch is a standard gear design parameter (used mostly in imperial/US gear systems) that describes the number of teeth per inch of pitch diameter — it determines tooth size and how gears of different sizes can mesh together.
The formula
Diametral pitch Pd = N / D, where N is the number of teeth and D is the pitch diameter in inches. From this, the metric module is calculated as m = 25.4 / Pd, circular pitch = π / Pd, and standard addendum = 1 / Pd.
These are standard AGMA gear design relationships; always verify against your specific gear standard or catalog before manufacturing.
Last reviewed August 2026