Mechanical Power Calculator
Compute rotational power from torque and rotational speed.
Formula
P = T × ω, ω = 2πN / 60
Inputs
- Torque (N·m)
- Rotational speed (RPM)
Notes and assumptions
- Shares its formula with Automotive's Torque / Power / RPM calculator — one engineering relationship, two entry points.
What it does
Rotational power from torque and speed: P = T × ω. It is the same relationship as the Torque / Power / RPM calculator.
Where it's used
Motors, pumps, fans and conveyor drives.
How to use it
- Enter the torque.
- Enter the rotational speed in rpm.
- Read the power.
The formula explained
- P
- power, W
- T
- torque, N·m
- ω
- 2πN / 60, rad/s
Worked example
A motor delivering 50 N·m at 2900 rpm.
Inputs:
- Torque: 50 N·m
- Rotational speed: 2900 RPM
The calculator gives:
- Result: 15184.4 W
- Power (kW): 15.184
Tips and common mistakes
- At the same torque, doubling the speed doubles the power.
- Motor nameplate power is the shaft output, not the electrical input.
- Allow for gearbox losses between motor and load.
Questions people ask
What is the formula with rpm?
P = 2π × N × T / 60, with N in rpm and T in N·m. 50 N·m at 2900 rpm is 2π × 2900 × 50 / 60 ≈ 15.2 kW.
How much torque does a motor give at its rated speed?
Rearrange the formula: T = P × 60 / (2π × N). A 7.5 kW motor at 1450 rpm gives about 49 N·m at the shaft.
How much electrical power does the motor draw?
Shaft power divided by the motor’s efficiency. A motor delivering 15.2 kW at 92 % efficiency takes about 16.5 kW from the supply.
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Enter your values to get the result with the formula, substituted values and an explanation of each step.