1 reference tool
Power, Torque & RPM Calculator and Drive Tools
Convert between shaft power, torque, and rotational speed in SI or imperial units, then continue to gear, pulley, shaft, and bearing calculations.
How are shaft power, torque, and RPM related?
For steady rotation, shaft power is torque multiplied by angular speed. Use the power–torque–RPM calculator to solve the missing quantity from the other two, with explicit SI and imperial unit conversion. Enter mechanical shaft power at the relevant location in the drive. Electrical input power, drive losses, start-up torque, and motor selection need additional information beyond this relationship.
Choose a calculator
- #004
RPM / Torque / Power Calculator
Calculate steady mechanical shaft power, torque, or RPM from the other two quantities, with metric and imperial unit conversion.
Before you use the result
- Identify the shaft and operating condition to which the power, torque, and speed refer. Values from different drive stages cannot be mixed directly.
- Select the missing quantity and use the displayed unit selectors. The calculator exposes the underlying rotational power relationship.
- Continue to the appropriate gear, belt, or shaft tool using consistent speed and torque assumptions, then verify component ratings and application limits.
Each linked tool includes its own formulas, worked examples, input units, limitations, and source notes. See how MechClarity documents and checks its calculations.
Continue with related calculations
- Gear Calculators: Ratio, Module, Dimensions & Forces — Calculate gear ratio, module and diametral pitch, spur gear dimensions, center distance, mesh forces, backlash, and simple planetary speeds.
- Belt & Pulley Calculators: Length, Speed & Ratio — Calculate V-belt datum length, timing-belt pitch length and tooth count, pulley speed ratio, belt speed, or pulley RPM with explicit diameter conventions.
- Shaft Calculators: Stress, Deflection & Critical Speed — Calculate shaft torsion, diameter, bending stress, bearing reactions, deflection, critical speed, key stress, and rigid flange coupling loads.