Gear Ratio Calculator
Enter the number of teeth on the driver and driven gears to calculate gear ratio, output RPM, torque multiplication, and speed.
100% client-side · no upload
Gear Ratio
Output RPM
Torque Multiplier
Output Torque
How to use
- Enter the number of teeth on the driver (input) gear and the driven (output) gear.
- Enter the driver's RPM to calculate the output shaft speed.
- Optionally enter input torque (Nm) to see the output torque after multiplication.
How gear ratios work
Gear ratio = driven teeth ÷ driver teeth. A ratio greater than 1:1 (e.g. 2:1) means the output shaft spins slower but with more torque — useful for climbing or high-load applications. A ratio less than 1:1 (e.g. 0.5:1) means the output spins faster with less torque — useful for high-speed applications.
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よくある質問
- Is the gear ratio calculator free?
- Yes, completely free with no signup and no usage limits.
- Does my data leave my device?
- No. All calculations run in JavaScript inside your browser. Nothing is sent to any server.
- Does it work on mobile?
- Yes. The tool is mobile-first and works on iPhone Safari and Android Chrome.