Horsepower & Torque Calculator

Convert between horsepower and torque at a given RPM, with the results in kW and N·m too. Enter either value to get the other. Calculates in your browser.

Horsepower

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Horsepower-
Torque (lb-ft)-
Power (kW)-
Torque (N·m)-

Show the math

Power and torque are tied together by engine speed:

hp = torque × RPM ÷ 5252

torque = hp × 5252 ÷ RPM

The two curves always cross at 5252 RPM, where horsepower equals torque. That's where the 5252 constant comes from. All math runs locally in your browser.

What this does

A horsepower and torque calculator converts between horsepower and torque at a given RPM, with the results in kW and N·m too. Enter either value to get the other.

How it works

With torque in lb-ft, horsepower equals torque times RPM divided by 5252. Rearranged, torque = hp × 5252 ÷ RPM, so you need the engine speed to convert between them.

Power = torque × RPM ÷ 5252

How to use it

  1. Enter the engine RPM.
  2. Enter horsepower or torque.
  3. Read the converted value.
  4. See the kW and N·m equivalents.

Understanding your result

The 5252 constant is why every dyno chart shows the hp and torque curves crossing at 5252 RPM. 1 hp ≈ 0.7457 kW and 1 lb-ft ≈ 1.3558 N·m.

Example

400 lb-ft at 5252 RPM is exactly 400 hp.

Sources & methodology

Last updated .

Frequently asked questions

How are horsepower and torque related?

Power = torque × RPM ÷ 5252 (with torque in lb-ft). Rearranged, torque = hp × 5252 ÷ RPM. You need the engine speed to convert between them.

Why 5252?

It comes from the definition of horsepower and the conversion between radians and revolutions. It is also why every dyno chart shows the hp and torque curves crossing at 5252 RPM.

What are kW and N·m?

The metric equivalents: 1 hp ≈ 0.7457 kW, and 1 lb-ft ≈ 1.3558 N·m. The tool shows both alongside the imperial figures.

Do you store my numbers?

No. All math runs locally in your browser.