Power Transmission Calculator

How it works

1. 1Enter the shaft torque in N·m (metric) or lbf·ft (imperial) and the rotational speed in rpm.
2. 2The calculator applies P = 2πNT/60, converting angular velocity ω = 2πN/60 and multiplying by torque to get power in watts.
3. 3Results are shown in kW or hp depending on your chosen unit system, with the raw watt value and angular velocity displayed as secondary stats.

Use cases

• Sizing electric motors and gearboxes for conveyors, pumps, and compressors.
• Verifying that a driveshaft or coupling can handle the rated power of a machine.
• Converting between torque-and-speed specifications and power ratings during mechanical design.

Frequently asked questions

What formula does the calculator use?

It uses P = 2πNT / 60, where N is shaft speed in rpm and T is torque in N·m. The result is power in watts. For example, 50 N·m at 1500 rpm gives P = 2π × 1500 × 50 / 60 ≈ 7854 W ≈ 7.85 kW.

How is this different from the Torque Calculator?

The Torque Calculator finds torque from power and speed. This calculator goes the other way — given torque and speed it tells you how much power the shaft is transmitting, which is the value needed to select motors, couplings, and driveline components.

Why does angular velocity matter?

Angular velocity ω (rad/s) is the physical quantity that links torque to power: P = T · ω. The rpm input is converted to rad/s internally via ω = 2πN/60. The secondary stat shows this value so you can use it directly in further mechanical calculations.