Guide
0-60 formula: how to calculate 0-60 time from horsepower and weight
There is a physics formula for the fastest a car could possibly reach 60 mph, and there is the slower time a real car posts. This guide shows both, with worked numbers, so you can see what the 0-60 calculator is doing for you.
The theoretical minimum
The least time a car can take is the energy needed to reach 60 mph divided by the power reaching the wheels: t = (½ × m × v²) ÷ (P × η). Use mass m in kilograms, v = 26.82 m/s (60 mph), power P in watts (1 hp = 745.7 W), and η for the share of engine power that reaches the wheels. Drivetrain losses are commonly quoted at 10 to 20 percent.
Worked example
A 3,900 lb car (1,769 kg) with 260 hp and 13 percent drivetrain loss. Kinetic energy at 60 mph is about 636 kJ. Wheel power is about 168.7 kW. Divide the two and the ideal time is about 3.8 seconds. That is a floor, not a prediction.
For 0-100 km/h, use v = 27.78 m/s instead. The same car needs about 683 kJ, so the ideal time is about 4.0 seconds. Because 100 km/h is 62.1 mph, the 0-100 km/h time is always a little longer than the 0-60 mph time for the same car.
Why real cars are slower
Tires slip at launch, gear changes interrupt drive, air drag grows with the square of speed, rolling resistance and road grade add loss, and engines do not make peak power at every rpm. A step-by-step simulation that includes these effects gives a far more realistic time, which is what the calculator runs in your browser.
0-60 time chart by horsepower and weight
This chart comes from the same simulation as the calculator. It assumes a rear-wheel-drive gasoline coupe with an automatic transmission and summer tires, on a dry, flat road at sea level and 68 °F, timed with the usual 1-ft rollout. Power is rated engine horsepower, and weight includes the driver.
| Horsepower | 2,500 lb | 3,000 lb | 3,500 lb | 4,000 lb | 4,500 lb |
|---|---|---|---|---|---|
| 100 hp | 11.2 | 13.4 | 15.8 | 18.5 | 21.0 |
| 150 hp | 7.3 | 8.6 | 10.3 | 11.8 | 13.4 |
| 200 hp | 5.3 | 6.5 | 7.6 | 8.5 | 9.6 |
| 250 hp | 4.6 | 5.0 | 5.9 | 6.7 | 7.6 |
| 300 hp | 4.1 | 4.5 | 5.0 | 5.6 | 6.3 |
| 350 hp | 3.8 | 4.1 | 4.5 | 4.9 | 5.3 |
| 400 hp | 3.8 | 3.9 | 4.1 | 4.4 | 4.7 |
Read across a row to see what extra weight costs, and down a column to see what extra power buys. Gains shrink as power rises, because the tires, not the engine, start to set the limit. Different tires, all-wheel drive, altitude or a manual gearbox move every number, so enter your own car in the 0-60 calculator for a result that fits it.
Power-to-weight ratio
Power-to-weight is horsepower divided by weight in thousands of pounds. For the car above, 260 ÷ 3.9 is about 66.7 hp per 1,000 lb. It ranks cars well, but it does not give a time on its own, because grip, gearing and drivetrain also matter.
Average acceleration from a 0-60 time
Average acceleration is 26.82 m/s divided by the time in seconds. A 6.0 second run averages about 4.47 m/s², or 0.46 g. Use the Measured time tab in the calculator to do this with your own speed and time.
Does gear ratio matter?
Yes. Gearing sets how engine power reaches the wheels at each speed and how many shifts you make before 60 mph, but it cannot add power. The calculator accounts for shift time through the transmission type you choose; it does not take individual gear ratios.
Common mistakes when estimating 0-60
- Mixing engine and wheel horsepower. Dyno numbers are measured at the wheels and are already lower than the rated figure. Tell the calculator which one you entered.
- Leaving out the driver. Curb weight excludes people and cargo. Add them, because 200 lb on a 3,500 lb car is almost 6 percent more mass.
- Comparing different timing methods. A 1-ft rollout removes roughly 0.2 to 0.3 seconds. Compare magazine numbers with rollout on and stopwatch numbers with it off.
- Ignoring conditions. Thin, hot air costs a naturally aspirated engine power, and a wet road can leave grip as the limit, not power.
Keep going
Run your own numbers, or move between the related guides.
Last updated: October 24, 2026. Estimates only; see the Terms.