UsefulVerse
Language · English

Free to use, no account

Gear Ratio Calculator

Calculate the speed reduction or increase from gear or sprocket teeth. Add up to six stages and optionally estimate output torque.

Use whole tooth counts, such as 20:40. Up to six stages; each stage’s driven part is assumed to share a shaft with the next stage’s driver.

Ideal ratio math, not a mechanical design or safety check. Without an efficiency value, torque is ideal. Real performance depends on the parts and installation. Gear direction assumes external meshes without idlers; chain direction assumes an uncrossed chain. Verify the design with component data and a qualified engineer.

How do I calculate a gear ratio?

Divide driven teeth by driver teeth. For example, 20 driving 40 gives a 2:1 reduction: 1,500 RPM becomes 750 RPM. In a multi-stage train, enter one pair per line; each driven member is assumed to share a shaft with the next driver.

Frequently asked questions

How do I calculate a gear ratio?

Divide driven teeth by driver teeth. For example, 20 driving 40 gives a 2:1 reduction: 1,500 RPM becomes 750 RPM. In a multi-stage train, enter one pair per line; each driven member is assumed to share a shaft with the next driver.

Are my transmission values uploaded?

No. The calculation runs in this browser; your values are not uploaded or saved.

What does a 2:1 gear ratio mean?

Under the convention used here, the driven gear has twice as many teeth as the driver. Output speed is half the input speed, and ideal torque is twice the input torque before losses.

Can I calculate a multi-stage gear train?

Yes. Enter up to six driver:driven pairs, one per line. This assumes each stage’s driven part is on the same shaft as the next stage’s driver; it does not model idlers or layout geometry.

Is the torque result real-world torque?

The default is ideal torque. If you enter a per-stage efficiency, the tool applies that assumption at every stage. Actual losses vary with the design, load, speed, lubrication and alignment.

Can I use this to size a safe transmission?

No. This is ratio arithmetic only. It does not verify tooth strength, shaft or bearing loads, materials, chain tension, guarding, standards or safety.