Engine Horsepower Calculator

Engine Horsepower – Quick Cheat Sheet

Mechanical horsepower: HP = (Torque(lb·ft) × RPM) / 5252.
Metric path: convert torque N·m → lb·ft with × 0.737562149, then apply the HP formula.
kW conversion: kW = hp × 0.7457 (rounded).
Drivetrain loss (optional): If your value is at the wheels, estimate crank HP as hp_crank = hp_wheel / (1 − loss%).
Typical loss ranges (rule of thumb): FWD 10–15%, RWD 12–18%, AWD 15–25% (varies by vehicle).
Data quality: Use torque at the same RPM you’re evaluating; dyno corrections and environment can affect results.

Notes & limits

5252 is derived from unit conversions (550 ft·lbf/s per hp and 2π rad/rev); the constant is standard in the U.S.
Loss% is a coarse estimate; real-world results vary with gearbox, diff, tire, and roller/road dyno method.
Inputs clamped to reasonable ranges (RPM ≤ 30,000; loss ≤ 40%).