Torque from Power Calculator
Convert rotational power and speed (RPM) into torque — the twisting force at an engine or motor shaft.
How it works
ω = 2π·N / 60 · τ = P / ω = P·60 / (2π·N)
Power is the rate of doing rotational work, and it equals torque multiplied by angular speed. Rearranged, torque is power divided by how fast the shaft spins — so at the same power, a slower-turning shaft carries more torque. This is why engines make peak torque and peak power at different RPMs, and why gearboxes trade speed for turning force.
Worked example
A 75 kW motor at 3,000 rpm turns at ω = 2π × 3,000 ÷ 60 = 314.2 rad/s, so torque = 75,000 ÷ 314.2 ≈ 238.7 N·m (about 176 lb·ft).
Sources: Torque — Wikipedia
Frequently asked questions
Why does torque fall as RPM rises for the same power?
Because power is torque times angular speed. If power is fixed, the two must trade off — spinning faster means each turn carries proportionally less twisting force.
What power unit should I use?
This field is in kilowatts. To convert from mechanical horsepower, multiply hp by 0.7457 to get kW (1 hp ≈ 0.746 kW).
Is this crankshaft or wheel torque?
It is the torque at whatever shaft the power and RPM describe. Gearing between that shaft and the wheels multiplies torque while dividing speed, so wheel torque differs by the gear ratio.
Related calculators
Educational estimate. Check the formula and units for your exact case.