Belts & Pulleys
Pulley Torque Ratio Calculator
Enter input torque and both pulley diameters to estimate the ideal torque change caused by the pulley ratio before losses.
Inputs
Formula
Ideal pulley torque ratio
Worked example
Using the default values shown in the calculator, the same formula gives the following result. This is a quick sanity check for the calculation, not a design recommendation.
Inputs
- Input torque
- 20 N*m
- Driver pulley diameter
- 100 mm
- Driven pulley diameter
- 250 mm
Result
- Ideal driven torque
- 50 N*m
Related calculators
Continue your workflow with a related calculation.
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Calculate driven pulley RPM from driver RPM and pulley diameters.
Power, Torque & Speed
Torque from Power and RPM Calculator
Calculate shaft torque from mechanical power and rotational speed.
Frequently asked questions
Does a larger driven pulley increase torque?
Ideally, yes. A larger driven pulley reduces speed and increases torque in the same ratio before losses.
Does this include belt efficiency or slip?
No. The result is an ideal ratio result. Apply measured or manufacturer efficiency separately for real output torque.