Instant power-to-weight ratio calculator. Enter horsepower and vehicle weight in lb or kg and get hp per lb or hp per kg.
What is Power-to-Weight Ratio?
The power-to-weight ratio (PWR) compares an engine’s output to the mass it must move. It’s calculated with a simple formula:
PWR = horsepower ÷ weight.
For example, a 200-hp car weighing 1,500 lb has a PWR of 0.133 hp/lb. Higher PWR generally means quicker acceleration and stronger performance.
How to use this tool
- Type your engine’s horsepower.
- Enter curb or race weight.
- Select pounds or kilograms; the result appears as hp per lb or hp per kg.
Power-to-Weight Calculator
| hp / lb (US) | 0.000 |
|---|---|
| hp / kg (Metric) | 0.000 |
| kW / kg (Eng.) | 0.000 |
| W / kg (SI) | 0.000 |
All four rows express the same ratio; they’re just different unit systems.
Enter horsepower and weight—everything updates instantly.
Understanding the multi-unit results
The calculator now displays four different units—hp / lb, hp / kg, kW / kg, and W / kg. Each figure represents the same power-to-weight ratio; only the measurement scale changes. Think of them as identical numbers written in four languages:
- hp / lb — popular with U.S. car media and drag-racing fans.
- hp / kg — the metric take you’ll see in European magazines.
- kW / kg — preferred by engineers and EV developers.
- W / kg — the base SI form, useful for drones and small motors.
No matter which line you quote, a higher number always means a lighter, more powerful machine. Use the unit that best matches your region, safe in the knowledge they’re all derived from the exact same inputs.
Why it matters
- Benchmarks acceleration potential across cars, bikes, or karts.
- Highlights gains from weight reduction as well as power upgrades.
- Helps racers classify vehicles into fair competition brackets.
Looking for more performance math and car tools? Try our Torque to HP calculator, Boost to HP estimator, and EV vs Gas Car Savings calculator.