Calculadora de Relação Potência-Peso
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
PWR = P/m
About this calculator
This calculator determines the power-to-weight ratio (PWR) of a vehicle or engine, measured in watts per kilogram (W/kg). PWR is a crucial performance indicator, especially for cars, motorcycles, and aircraft, as it shows how much power is available per unit of mass. Higher values indicate better acceleration and climbing ability.
The calculation is simple: divide total power (in watts) by total mass (in kilograms). For example, a car with 150,000 W (about 201 hp) and 1,200 kg has a PWR of 125 W/kg. This metric is more relevant than raw power because a light vehicle with moderate power can outperform a heavier one with higher power.
Use this calculator to compare vehicles, optimize engineering designs, or evaluate modifications. It is common in automotive competitions, electric bicycle projects, and light aircraft performance analysis. Ensure consistent units: power in watts and mass in kilograms.
Caution: use real wheel (or shaft) power, not engine gross power, which includes losses. Also, mass should include load, fuel, and occupants. For conversions, 1 hp = 745.7 W (mechanical) or 735.5 W (metric).
Frequently asked questions
What is the difference between engine power and wheel power?
Engine power is measured at the crankshaft without losses. Wheel power is what actually reaches the ground, after drivetrain losses, typically 15-20% lower.
How do I convert horsepower (hp) to watts?
Multiply the hp value by 745.7. For example, 100 hp × 745.7 = 74,570 W.
Is power-to-weight ratio useful for comparing electric and combustion cars?
Yes, but electric cars have instant torque, which may give an advantage at low speeds. PWR is still a good overall performance indicator.
What is considered a good power-to-weight ratio for a passenger car?
Generally, above 100 W/kg is good. Sports cars can exceed 250 W/kg.
Should I include the driver's weight in the calculation?
Yes, for realistic analysis, include total weight: vehicle, passengers, cargo, and fuel.