Torque, Power & Speed Calculator
By Santaji GadepatilinUpdated October 27, 2026
Torque (N·m) vs Speed — other inputs held at your current values.
How to use this calculator
Enter any two of power, speed and torque to get the third. Switch units freely — kW or hp, N·m or lbf·ft.
The formula
P = 2π n T ÷ 60 → T = 9549 × P(kW) ÷ n(rpm)
Worked example
An 11 kW, 4-pole motor running at 1,460 rpm:
T = 9549 × 11 ÷ 1460 = 71.9 N·m
Through a 10:1 gearbox (95% efficient) the output is about 146 rpm and 683 N·m.
Typical motor speeds at 50 Hz
| Poles | Synchronous | Typical full-load |
|---|---|---|
| 2 | 3,000 rpm | ~2,900 rpm |
| 4 | 1,500 rpm | ~1,460 rpm |
| 6 | 1,000 rpm | ~970 rpm |
| 8 | 750 rpm | ~730 rpm |
At 60 Hz, multiply speeds by 1.2.
Why it matters
Low-speed applications such as conveyors, mixers and winches need high torque. Selecting the motor on kW alone can leave it unable to start the load — always check torque at the driven speed.
Frequently asked questions
What is the formula linking torque, power and speed?
P = 2π × n × T ÷ 60, with P in watts, n in rpm and T in N·m. A handy form is T (N·m) = 9549 × P (kW) ÷ n (rpm).
How does a gearbox change torque?
Ignoring losses, power stays the same. Reducing speed by a ratio of 10:1 increases torque by about 10 times.
What is the hp version?
T (lbf·ft) = 5252 × P (hp) ÷ n (rpm). Switch the units in the calculator to use it.