Pulley and gear ratio
Calculate output shaft speed and ideal torque multiplication across up to six drive stages. Drag the graph handles to change inputs and explore the result.
Your inputs
Example values are editable. Use your measurements and product specifications. Results update as you edit.
Calculations run in your browser. Inputs are not saved or sent to analytics.
How it works
- rstage = / ; rtotal = Π(rstage)
- noutput = / rtotal; Toutput / Tinput = rtotal
Input and formula key
Your result
Complete the inputs to see your result.
Assumptions and limitations
Use pulley pitch diameters in the same unit or integer gear teeth from 2–1,000. Each driven shaft feeds the next stage. Ideal no-slip drive; torque factor assumes no power losses. Does not calculate belt length, tension, tooth geometry or capacity. 50 driving 100 at 1,200 rpm gives 600 rpm and an ideal 2× torque factor.
Sources
- OpenStax — rotational kinematics Sources reviewed: 2026-10-10
- OpenStax — work and power for rotational motion Sources reviewed: 2026-10-10
