How do you calculate torque from horsepower and RPM?

Use Torque (lb·ft) = Horsepower × 5252 ÷ RPM. The 5252 constant comes from converting radians and horsepower definitions so power, torque, and engine speed stay consistent in imperial units.

Why is peak torque at a different RPM than peak horsepower?

Torque is twisting force at the crank; horsepower is torque × RPM. Many engines make max torque earlier in the rev range, then horsepower keeps climbing as RPM rises even while torque falls off.

Should I use lb·ft or N·m?

North American dyno sheets and OEM catalogs usually quote lb·ft. European and SI specs use N·m. This calculator converts both (1 lb·ft ≈ 1.356 N·m) so you can match the unit on your dyno chart or parts listing.

Can I enter power in kilowatts instead of horsepower?

Yes. Toggle to kW and enter brake power; the tool converts to horsepower internally (1 hp ≈ 0.746 kW), runs the torque formula, and can display the result in lb·ft or N·m.

Is this the same as wheel torque or crank torque?

This is crank (flywheel) torque from brake horsepower and RPM — the same relationship used on engine dyno sheets. Wheel torque after the transmission and axle is higher by the gear ratios and lower by drivetrain losses.

Torque Calculator

Convert brake horsepower and RPM into crank torque — lb·ft or N·m, with hp/kW unit toggles.

Convert brake horsepower and RPM into crank torque — dyno-sheet style.

Power & engine speed

Use the RPM where that power was measured for a meaningful torque figure.

Power (hp)

Engine RPM

Dyno cell · brake torque

Torque from power & RPM

Dyno estimate

Calculated torque

382

lb·ft · 382 lb·ft · 517.9 N·m

Power
400
hp · 298.3 kW
Engine speed
5500
RPM

Formula: Torque (lb·ft) from power × 5252 ÷ RPM

Crank torque from brake power. Wheel torque after the gearbox and axle is a different number.

Torque from horsepower and RPM

Torque (lb·ft) = HP × 5252 ÷ RPM — the same relationship dyno sheets use.
Peak torque and peak horsepower rarely share the same RPM; pick the speed that matches your power figure.
Toggle lb·ft / N·m and hp / kW to match OEM specs or a European dyno printout.

Horsepower alone does not tell you how hard the crank is twisting at a given engine speed. This free torque calculator solves the classic brake-power relationship so you can turn a dyno HP number (or a solid estimate) and an RPM into crank torque in pound-feet or newton-meters.

Enter power and the RPM where it was measured. The dyno-cell view shows the calculated torque with power and engine speed alongside so you can sanity-check a cam swap, turbo map, or gearing discussion without digging out a slide rule. Defaults of 400 hp at 5500 rpm land near 382 lb·ft — a familiar street-performance ballpark.

Remember this is flywheel torque from brake power, not wheel torque after the transmission and axle. Pair the result with the horsepower calculator for the reverse check, or with gear-ratio and RPM-at-speed tools when you care about tractive effort on the road.

How to use the torque calculator

Enter brake horsepower or kilowatts. Use crank/flywheel power from a dyno sheet or a trusted estimate — not a marketing “crank HP” guess if you care about accuracy.
Enter engine RPM. Use the RPM at which that power figure was measured (peak HP RPM for peak-power torque, or another point if you want torque at that speed).
Read torque in the dyno cell. Switch lb·ft / N·m as needed and compare with your gearing or horsepower calculator for the reverse check.

Torque Calculator

Torque from horsepower and RPM

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