Shaft Torque Calculator Formula

Understand the math behind the shaft torque calculator. Each variable explained with a worked example.

Use the Shaft Torque Calculator

Formulas Used

Shaft Torque

torque = power_kw * 1000 * 60 / (2 * pi * rpm)

Variables

VariableDescriptionDefault
power_kwShaft Power (P)(kW)15
rpmRotational Speed(RPM)1500

How It Works

Shaft Torque from Power and Speed

When power and speed are known, torque can be back-calculated.

Formula

T = P / omega = P x 60 / (2 pi N)

where P is power in watts, N is speed in RPM, and T is torque in N-m. This is essential for sizing shafts, couplings, and gearboxes.

Worked Example

A 15 kW motor running at 1500 RPM.

power_kw = 15rpm = 1500
  1. 01P = 15,000 W
  2. 02T = 15,000 x 60 / (2 x pi x 1500)
  3. 03T = 900,000 / 9424.8 = 95.49 N-m

Ready to run the numbers?

Open Shaft Torque Calculator