Diametral pitch to circular pitch in inches
Type a value in DP to get it in CP (in) instantly.
0.3142CP (in)
That's 1.02× as coarse as a car gearbox, while a truck final drive is 2.4× coarser. A 20-tooth gear of this size would be 50.8 mm across.
What it means
How big are those teeth?
Module and pitch describe tooth size only. Gears also need the same pressure angle, usually 20°, before they will run together.
The math
How to convert DP to CP (in)
Module and diametral pitch are reciprocals through the inch: module = 25.4 ÷ DP. Circular pitch follows as CP = π × module.
Example: 10 DP = 0.314159 CP (in).
Every unit
Your tooth size in every unit
Tables
DP to CP (in) conversion table
| DP | CP (in) |
|---|---|
| 0.5 DP | 6.28319 CP (in) |
| 0.8 DP | 3.92699 CP (in) |
| 1 DP | 3.14159 CP (in) |
| 1.25 DP | 2.51327 CP (in) |
| 1.5 DP | 2.0944 CP (in) |
| 2 DP | 1.5708 CP (in) |
| 2.5 DP | 1.25664 CP (in) |
| 3 DP | 1.0472 CP (in) |
| 4 DP | 0.785398 CP (in) |
| 5 DP | 0.628319 CP (in) |
| 6 DP | 0.523599 CP (in) |
| 8 DP | 0.392699 CP (in) |
| 10 DP | 0.314159 CP (in) |
CP (in) to DP conversion table
| CP (in) | DP |
|---|---|
| 0.5 CP (in) | 6.28319 DP |
| 0.8 CP (in) | 3.92699 DP |
| 1 CP (in) | 3.14159 DP |
| 1.25 CP (in) | 2.51327 DP |
| 1.5 CP (in) | 2.0944 DP |
| 2 CP (in) | 1.5708 DP |
| 2.5 CP (in) | 1.25664 DP |
| 3 CP (in) | 1.0472 DP |
| 4 CP (in) | 0.785398 DP |
| 5 CP (in) | 0.628319 DP |
| 6 CP (in) | 0.523599 DP |
| 8 CP (in) | 0.392699 DP |
| 10 CP (in) | 0.314159 DP |
Quick answers
Quick answers
- How many CP (in) is 1 DP?
- 1 DP is 3.14159 CP (in).
- How many CP (in) is 10 DP?
- 10 DP is 0.314159 CP (in).
The units
About these units
Diametral pitch (DP)
Teeth per inch of pitch diameter, the US standard. Bigger means finer.
Circular pitch in inches (CP (in))
The same spacing in inches, used for chain sprockets and timing belts.
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