Torque in lb-ft equals horsepower × 5252 divided by engine speed in rpm. For example, 300 hp at 4,000 rpm gives 300 × 5252 ÷ 4000 = 394 lb-ft, or about 534 N·m. Power and torque must be read at the same rpm; peak horsepower and peak torque usually occur at different engine speeds.
Spec sheets often list peak power but leave torque out, or quote it at a different engine speed. This calculator turns a power figure at a known rpm into the torque the crankshaft delivers at that same rpm. Enter power in mechanical horsepower, kilowatts or metric PS, add the engine speed, and the tool returns torque in lb-ft and N·m along with the power restated in hp and kW. It suits tuners reading a dyno printout, students checking a rotating-machinery problem, and anyone comparing a European PS rating with an American hp one. The limit: it gives torque at one operating point only. It cannot recover the peak torque of an engine from its peak horsepower, because the two peaks almost never share an rpm.
Type the power figure and pick hp, kW or PS from the unit menu inside the field.
Use the rpm at which that power was measured, not the redline or idle speed.
Torque in lb-ft is the main figure; N·m and the power in both hp and kW appear below, with the working steps.
Result Torque: 300.0
Torque (N·m): 406.8
Power in mechanical hp: 300
Power in kW: 223.7
At 5,252 rpm the horsepower and lb-ft curves on any dyno sheet cross, so 300 hp means 300 lb-ft.
Result Torque: 117.4
Torque (N·m): 159.2
Power in mechanical hp: 134.1
Power in kW: 100
A small turbo four making 100 kW near the redline produces about 159 N·m there, well under its mid-range peak.
Result Torque: 259.0
Torque (N·m): 351.2
Power in mechanical hp: 197.3
Power in kW: 147.1
European spec sheets quote PS; 200 PS is 197.3 hp, giving 259 lb-ft (351 N·m) at 4,000 rpm.
T = P ÷ ω, with ω = 2π × rpm ÷ 60; in US units T(lb-ft) = hp × 5252.113 ÷ rpm
TPωrpmPower is torque multiplied by angular speed. The tool converts the power to watts, the rpm to radians per second, and divides to get N·m, then divides by 1.35582 to give lb-ft. The constant 5252.113 is 33,000 ft·lbf/min per hp divided by 2π, which is why hp and lb-ft are equal at 5,252 rpm.
One horsepower is 33,000 ft·lbf per minute. Dividing by 2π to turn revolutions into radians gives 5252.1, so hp × 5252 ÷ rpm equals hp exactly when rpm is 5252. Any dyno chart plotted in hp and lb-ft on the same scale shows the curves crossing there.
No. Peak power usually arrives well above peak torque on the rev range. Using the peak hp figure gives the torque at the rpm of peak power, which is lower than the engine's maximum torque.
Mechanical horsepower is 745.7 W, based on 550 ft·lbf per second. PS, the metric horsepower used in Germany and much of Europe, is 735.5 W. A 200 PS engine therefore makes about 197 hp.
Multiply lb-ft by 1.35582. For example, 300 lb-ft is about 406.7 N·m. The calculator shows both values so no separate conversion is needed.
It gives torque at the shaft where the power was measured. Wheel torque is that figure multiplied by the gear ratio and final-drive ratio, minus drivetrain losses that typically run 10 to 20 percent.
Yes, T = P ÷ ω applies to any rotating shaft. Enter the motor's output power in kW at a given rpm. Below the base speed, motor torque is capped by the controller, so the calculated figure only holds in the constant-power region.
Using this tool in an assignment, article or report? Copy a citation, or a link for your website.
Tools Directory Editorial Team. (2026, October 13). Horsepower to Torque. Tools Directory. Retrieved October 26, 2026, from https://tools.milunir.com/automotive/engine-and-performance/horsepower-to-torque/
Tools Directory Editorial Team. “Horsepower to Torque.” Tools Directory, 13 Oct. 2026, https://tools.milunir.com/automotive/engine-and-performance/horsepower-to-torque/. Accessed 26 Oct. 2026.
Tools Directory Editorial Team. “Horsepower to Torque.” Tools Directory. Last modified October 13, 2026. Accessed October 26, 2026. https://tools.milunir.com/automotive/engine-and-performance/horsepower-to-torque/.
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