Sprocket Pitch Diameter Calculator

Inputs

View results
Number of teeth on the sprocket. Small sprockets run rougher and wear chain faster.
Roller-chain pitch. ANSI #40 chain is 12.7 mm or 1/2 in.
mm
Optional rotational speed used to estimate chain pitch-line speed.
rpm

Results

Default result
Edit inputs
Pitch diameter(PD)
61.08mm
Caution

Small sprocket; expect more polygonal action and faster chain wear than a 17+ tooth sprocket.

PD = p / sin(180°/N).

Also computed

Pitch radius(r)30.54mm

Chain travel per rev(s/rev)190.5mm

N x p, not outside circumference.

Chain speed(v)3.175m/s

Pitch-line speed from chain pitch travel, not tip diameter.

v = N x p x n / 60000.

Tooth pitch angle(theta)24deg

360° / 15 teeth.

Method notes 4 notes
  • Pitch diameter is the theoretical circle through the chain roller centers: PD = p/sin(180°/N).
  • A roller chain advances one pitch per engaged tooth, so chain travel per revolution is N*p.
  • Pitch diameter is not outside diameter or tip diameter. Tooth form, roller seating and manufacturer drawings control measured outside diameter.
  • Use the ratio, length, tension and overhung-load tools after this geometry screen for a complete drive check.

Powered by MachineCalcs ↗