Power-to-weight ratio is the single best predictor of acceleration and climbing ability. A cyclist producing 4 W/kg climbs faster than a heavier rider with more watts; a light sports car can outrun a more powerful but heavier one.
How to use the Power-to-Weight Ratio Calculator
- Power
- Weight
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Enter the power and the mass (including driver or rider). The ratio is given in several common forms.
Inputs explained
| Field | What to enter |
|---|---|
| Power | Units: hp, kW, W, PS |
| Weight | Units: kg, g, mg, t, lb, oz |
What each result means
- Power-to-weight ratio = [Power]÷[Weight]
- Horsepower per tonne = [Power]÷745.69987158227÷([Weight]÷1000)
- Weight per horsepower = [Weight]÷([Power]÷745.69987158227)
- Pounds per horsepower = [Weight]÷0.45359237÷([Power]÷745.69987158227)
Example values
How the main result changes when Power changes and everything else stays at the example values above:
| Power (hp) | Power-to-weight ratio (W/kg) |
|---|---|
| 150 | 79.896 |
| 225 | 119.845 |
| 300 | 159.793 |
| 375 | 199.741 |
| 450 | 239.689 |
| 600 | 319.586 |
Formula
PWR = P / m
Worked example
Inputs — Power: 300 hp; Weight: 1,400 kg.
Results — Power-to-weight ratio = 159.793 W/kg; Horsepower per tonne = 214.29 hp/t; Weight per horsepower = 4.667 kg/hp; Pounds per horsepower = 10.288 lb/hp.
Key terms
- Power-to-weight ratio
- Power divided by mass.
Frequently asked questions
What is a good power-to-weight ratio for a car?
Family cars: 50–100 hp/t; sports cars: 200–400 hp/t; hypercars: over 600 hp/t.
What W/kg do cyclists produce?
Amateurs 2–3 W/kg for an hour; professionals 5.5–6.5 W/kg.
Is a higher ratio always better?
For acceleration yes, but traction and aerodynamics also matter.
Should I include the driver?
Yes – the mass actually being accelerated.