KEVOS® MAKEOS · Gears
Roller Chain Sprocket Diameters
What are the pitch, outside, bottom and caliper diameters of this sprocket?
Pitch diameter, approximate outside diameter, bottom diameter and caliper diameter (for odd tooth counts) of a roller chain sprocket from chain pitch, tooth count and roller diameter.
Open the calculatorRuns in your browser. No account needed.
How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Chain pitch | mm | Chain pitch (15.875 mm for 10B/ANSI 50, 12.7 mm for 08B/ANSI 40). |
| Number of teeth | teeth | Tooth count of the sprocket. |
| Roller diameter | mm | Roller diameter of the chain from its data sheet. |
Method and formulas
- Pitch diameter = p ÷ sin(180° ÷ N).
- Bottom diameter = PD − roller diameter.
- Caliper diameter (odd N) = PD cos(90° ÷ N) − roller diameter; outside diameter ≈ p (0.6 + cot(180° ÷ N)).
- Example: 17 teeth on 15.875 mm pitch: PD 86.395 mm, bottom 76.235 mm.
Limitations
- The outside diameter is the ANSI approximate value; tooth form tolerances come from the chain standard.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Machine or inspect sprockets
- Check clearances around a sprocket
- Measure worn sprockets
Who it is for
- Gear designers
- Machinists
- Maintenance engineers
What you get
- Pitch diameter
- Approximate outside diameter
- Bottom diameter
- Caliper diameter (odd teeth)
Interpreting the result
- Measure worn sprockets across the bottoms (or caliper for odd teeth) and compare with these values.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2537–2550. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
