Shaft Power Calculator Formula

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

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Formulas Used

Shaft Power

power_w = torque * omega

Shaft Power

power_kw = torque * omega / 1000

Shaft Power

power_hp = torque * omega / 746

Variables

VariableDescriptionDefault
torqueShaft Torque (T)(N-m)100
rpmRotational Speed(RPM)1500
omegaDerived value= 2 * pi * rpm / 60calculated

How It Works

Shaft Power from Torque and Speed

Rotational power is the product of torque and angular velocity.

Formula

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

where T is torque in N-m, N is speed in RPM, and P is power in watts. Dividing by 1000 gives kilowatts. One horsepower equals 746 watts.

Worked Example

A shaft transmitting 100 N-m torque at 1500 RPM.

torque = 100rpm = 1500
  1. 01omega = 2 x pi x 1500 / 60 = 157.08 rad/s
  2. 02P = 100 x 157.08 = 15,708 W = 15.71 kW
  3. 03P = 15,708 / 746 = 21.06 hp

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