Module
mm
Metric tooth-size convention.
Mechanics · Transmission and rotation
Gear Module ↔ Diametral Pitch Converter
Choose the conversion direction and enter one tooth-size convention.
Created v1.0
By Thibaut Grzelak, Mechanical Analysis Engineer
02
Results
Diametral pitch
teeth/in
Teeth per inch of pitch diameter.
Relation and numerical substitution
Pd = 25.4 / m ; m = 25.4 / Pd—
m is expressed in millimetres. Pd is expressed in teeth per inch of pitch diameter. Both quantities are strictly positive. The conversion does not calculate tooth count or a gear diameter.
01Formulas and symbols
Formulas used
Pd
25.4 / mDiametral pitch from module in millimetresm
25.4 / PdModule in millimetres from diametral pitch02Assumptions and limits
Scope of validity
- m is expressed in millimetres.
- Pd is expressed in teeth per inch of pitch diameter.
- Both quantities are strictly positive.
- The conversion does not calculate tooth count or a gear diameter.
03Validation example
Reference numerical case
- m = 2.54 mm gives Pd = 10 teeth/in.
- Pd = 8 teeth/in gives m = 3.175 mm.
- The inverse conversion returns the starting value.
04References
Technical references
- SDP/SI, Elements of Metric Gear Technology, section 2.5.
- KHK Gears, Comparison of Pitch.