Power-to-Weight Ratio Calculator
Calculate power-to-weight ratio in HP/lb, HP/ton, kW/kg, and PS/kg. Compare against vehicle class benchmarks from economy cars to hypercars.
Curb weight or weight with driver for performance comparisons.
Why Power-to-Weight Ratio Matters
Power-to-weight ratio is the single best predictor of straight-line acceleration. Two vehicles with identical power-to-weight ratios will accelerate at roughly the same rate regardless of whether one is a 200 HP lightweight or a 600 HP heavyweight. It's the great equalizer in performance comparisons.
Common Formats
- HP/lb: Used in the US. Typical range is 0.03 (economy car) to 0.25+ (hypercar).
- HP/ton: Also common in the US. Multiply HP/lb by 2000. Produces more intuitive numbers (60-500+ range).
- kW/kg: Standard in engineering and European contexts.
- PS/kg: Common in Japanese and some European markets (PS is metric horsepower).
Benchmarks
- Economy car: ~0.04 HP/lb (80 HP/ton) — Honda Fit, Toyota Corolla
- Average sedan: ~0.06 HP/lb (120 HP/ton) — Camry, Accord
- Sports car: ~0.09 HP/lb (180 HP/ton) — Mustang GT, WRX STI
- Muscle/performance: ~0.12 HP/lb (240 HP/ton) — Corvette, GT-R
- Supercar: ~0.18 HP/lb (360 HP/ton) — Ferrari 488, Lamborghini Huracan
- Hypercar: ~0.25 HP/lb (500 HP/ton) — Bugatti Chiron, Koenigsegg Jesko
Weight Reduction vs. Power Addition
Removing weight improves acceleration, braking, handling, and fuel economy simultaneously. Adding horsepower only helps acceleration. As a rough equivalence, removing 100 lbs provides a similar acceleration improvement to adding 10–15 HP on a typical 3500 lb car. The lighter car also benefits in every corner and braking zone.
Frequently Asked Questions
How is power-to-weight ratio calculated?
Divide the vehicle's horsepower by its weight. In the US, it's typically expressed as HP per pound or HP per ton. A 400 HP car weighing 3500 lbs has a ratio of 0.114 HP/lb or 228.6 HP/ton. Higher is better — a lighter car with the same power will always accelerate harder than a heavier one.
What is a good power-to-weight ratio?
For street cars: under 0.05 HP/lb is slow, 0.06-0.08 is average, 0.09-0.12 is sporty, 0.12-0.18 is fast (Corvette, GT-R), and above 0.18 is supercar territory. For reference, a Bugatti Chiron is about 0.23 HP/lb, and an F1 car is around 0.60 HP/lb.
Is it better to add power or reduce weight?
Removing weight improves acceleration, braking, and handling simultaneously. Adding power only improves acceleration (and can hurt braking and handling). As a rule of thumb, removing 100 lbs has a similar acceleration benefit to adding 10-15 HP on a typical car. Weight reduction is usually more cost-effective for the first 100-200 lbs.
What is the difference between HP/lb and HP/ton?
They express the same ratio at different scales. HP/ton uses the short ton (2000 lbs). To convert: HP/ton = HP/lb × 2000. A car with 0.10 HP/lb has 200 HP/ton. HP/ton produces more intuitive numbers — most people find '200 HP/ton' easier to grasp than '0.10 HP/lb'.
Related Articles
How quarter-mile elapsed time and trap speed work, what determines your ET, and the most effective ways to go faster — from weight reduction to traction to power adders.
GeneralPower-to-Weight Ratio: Why It Matters More Than Peak HorsepowerWhy power-to-weight ratio is the best single predictor of acceleration, how to calculate it, where your car sits relative to common benchmarks, and whether to add power or subtract weight.
Related Calculators
Convert between horsepower and torque at a given RPM. Also calculate HP from trap speed or ET and vehicle weight.
0-60 TimeEstimate 0-60 mph time from horsepower, vehicle weight, and drivetrain type. Compares against common performance benchmarks.
Quarter MileEstimate quarter-mile elapsed time and trap speed from vehicle weight and horsepower. Includes 1/8 mile estimates.
Dyno CorrectionCalculate dyno correction factors using SAE J1349, DIN 70020, and STD methods from temperature, barometric pressure, and humidity. Convert between corrected and observed HP.