Power-to-weight ratio calculator
Enter a car’s weight and power to get its power-to-weight ratio in pounds per horsepower and kilowatts per tonne, and see how it ranks next to real cars.
Work out power to weight
Power to weight
7.8 lb per hp
258 hp per ton (2,000 lb)
- Metric212 kW per tonne
- Horsepower per pound0.129
- Weight3,900 lb
Next to real cars (curb weight per rated horsepower)
Fewer pounds per horsepower is quicker. 11 cars’ weights and power from their makers and Car and Driver’s tests.
Turn it into a quarter-mile time
Power to weight: 7.8 lb per hp
The weight on a spec sheet, without a driver. Power is the rated figure at the engine, or the motors’ combined rating for an EV.
What power to weight tells you
Power to weight is a car’s weight divided by its power: pounds per horsepower, where lower is quicker, or the other way up, as horsepower per ton or kilowatts per tonne. It’s the main thing that sets a car’s speed at the end of a quarter mile; the classic quarter-mile formulas use nothing else. It says less about 0-60, where grip, drive and launch matter as much.
lb per hp = weight (lb) ÷ hp
kW per tonne = kW ÷ (weight in kg ÷ 1,000)
How weight per horsepower predicts the quarter mile (Jeff Lucius)
Real cars, by power to weight
| Car | Curb weight | Power | lb per hp | kW per tonne |
|---|---|---|---|---|
| Rimac Nevera | 5,070 lb | 1,914 hp | 2.6 | 621 |
| Model S Plaid | 4,830 lb | 1,020 hp | 4.7 | 347 |
| BMW M4 Competition | 3,900 lb | 503 hp | 7.8 | 212 |
| BMW M3 Competition | 3,930 lb | 503 hp | 7.8 | 210 |
| BMW M2 (manual) | 3,750 lb | 473 hp | 7.9 | 207 |
| BMW M2 (auto) | 3,810 lb | 473 hp | 8.1 | 204 |
| Cyberbeast | 6,900 lb | 834 hp | 8.3 | 199 |
| Model Y Performance | 4,440 lb | 510 hp | 8.7 | 189 |
| Cybertruck AWD | 6,640 lb | 600 hp | 11.1 | 149 |
| Model Y Long Range | 4,420 lb | 397 hp | 11.1 | 148 |
| Honda Civic Sport | 2,910 lb | 158 hp | 18.4 | 89 |
Each car links to the road test or maker’s figures its weight and power come from.
More calculators
Tested times and mods, car by car
Questions
What is a good power-to-weight ratio?
About 18.4 lb per hp for an everyday Honda Civic Sport, 7.8 for a BMW M4 Competition, 4.7 for a Tesla Model S Plaid and 2.6 for the Rimac Nevera, by curb weight and rated power.
Curb weight or weight with the driver?
Curb weight, to compare with published figures, since spec sheets use it. For quarter-mile and 0-60 estimates, use the weight with the driver.
hp per ton or kW per tonne?
They say the same thing in different units. A US ton is 2,000 lb and a metric tonne is 1,000 kg; one horsepower is 745.7 watts.
Does a better ratio always mean a quicker car?
For trap speed, nearly: the classic quarter-mile formulas use nothing else. For 0-60 it matters less, because grip, drive and launch hold most fast cars back below 60 mph.