Power-to-Weight Ratio Calculator
Compare an engine to the mass it has to move, in hp per ton, kW per kg, and lbs per hp.
Power-to-weight ratio explains why a light car with a modest engine can feel quicker than a heavy one with more power. Enter the power output and the vehicle weight, each in the unit you prefer, and this tool shows the ratio three ways and tags roughly where the number lands. It all runs in your browser, and nothing is sent anywhere.
How it is calculated
The headline figure is horsepower spread across each US ton (2,000 lbs) of weight:
Power-to-weight = horsepower ÷ (weight in lbs ÷ 2,000)
Your entries are first converted to a common base. Power in kW is multiplied by 1.34102 and PS by 0.98632 to reach horsepower; weight in kg is multiplied by 2.20462, and tons are converted to pounds. For example, 300 hp in a 3,000 lb car is 300 ÷ (3,000 ÷ 2,000) = 200 hp per ton. The tool also shows the same relationship as kW per kg and as lbs per hp.
Reading the performance tag
Below the numbers a label places the result on a rough scale based on horsepower per ton: under 120 reads as a standard commuter, 120 and up as a high-performance daily, 200 and up as sports-car territory, 350 and up as supercar, and 500 or more as hypercar. These bands are a plain-language guide, not an official rating, and the same ratio can feel very different depending on gearing, grip, and aerodynamics.
Mixing units
Power can be entered in hp, kW, or PS, and weight in pounds, kilograms, US tons, or metric tons, in any combination. Use a curb or kerb weight for a realistic figure; adding a driver, passengers, and fuel lowers the ratio, which is why race figures often quote a lighter number than a showroom spec sheet.
Frequently Asked Questions
What is a good power-to-weight ratio?
It depends on the vehicle. As a rough guide the tool treats 200 hp per ton as sports-car level and 350 and above as supercar territory, but gearing and traction matter too.
Can I mix metric and imperial units?
Yes. Choose any power unit and any weight unit; the tool converts both to a common base before working out the ratio.
Should I use curb weight or loaded weight?
Either works. Curb weight is the usual reference, and adding occupants and fuel will lower the ratio you see.
Does this calculator store my data?
No. Everything runs in your browser and nothing is uploaded or saved.