Pitch Diameter Calculator

Find the pitch diameter of a gear.

Pitch diameter 2.5

Formula: PD = teeth ÷ diametral pitch

Step-by-step with your numbers:

1. Values used:

2. Number of teeth = 30

3. Diametral pitch (DP) = 12

5. Pitch diameter = Number of teeth / Diametral pitch (DP) = 30 / 12 = 2.5

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Find the pitch diameter — the circle where gear teeth ideally mesh.

The math behind it

PD = number of teeth ÷ diametral pitch. DP = teeth per inch of pitch diameter.

30 teeth, DP 12 → 2.5 in.

Module instead?

In metric, module = 25.4 ÷ DP; pitch diameter = module × teeth (mm).