Power to Weight Ratio Calculator
Calculate power-to-weight ratio in lb per hp, hp per 1,000 lb, hp per tonne and hp per US ton.
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What this tool does
Calculate power-to-weight ratio in lb per hp, hp per 1,000 lb, hp per tonne and hp per US ton. Use a consistent weight basis (curb or with-driver) when comparing vehicles; the ratio alone says nothing about gearing or traction.
How to use the Power to Weight Ratio Calculator
- Enter or select vehicle weight (lb).
- Enter or select horsepower.
- Read the calculated result; change any measurement to compare alternatives.
Formula
lb per hp = weight ÷ hp; hp per 1,000 lb = hp ÷ weight × 1000; hp per tonne = hp ÷ (weight in kg ÷ 1000)
- weight
- Vehicle weight (lb)
- hp
- Horsepower
Use a consistent weight basis (curb or with-driver) when comparing vehicles; the ratio alone says nothing about gearing or traction.
Worked example
For power to weight ratio calculator, the following measurements illustrate the exact method: Vehicle weight (lb): 3500; Horsepower: 300.
Inputs
- Vehicle weight (lb)3500
- Horsepower300
Result
- Weight per horsepower (lb/hp)11.67
- Horsepower per 1,000 lb85.71
- Horsepower per tonne188.97
- Horsepower per US ton171.43
Results explained
- Weight per horsepower (lb/hp)
- Weight per horsepower (lb/hp) from the formula above. Use a consistent weight basis (curb or with-driver) when comparing vehicles; the ratio alone says nothing about gearing or traction.
- Horsepower per 1,000 lb
- Horsepower per 1,000 lb from the formula above. Use a consistent weight basis (curb or with-driver) when comparing vehicles; the ratio alone says nothing about gearing or traction.
- Horsepower per tonne
- Horsepower per tonne from the formula above. Use a consistent weight basis (curb or with-driver) when comparing vehicles; the ratio alone says nothing about gearing or traction.
- Horsepower per US ton
- Horsepower per US ton from the formula above. Use a consistent weight basis (curb or with-driver) when comparing vehicles; the ratio alone says nothing about gearing or traction.
Frequently asked questions
Either direction: pounds per horsepower = weight ÷ power (lower is faster), or horsepower per ton = power ÷ weight in tons (higher is faster). A 3,500 lb, 300 hp car is 11.7 lb/hp, or about 171 hp per US ton.
Rough road-car landmarks: economy cars 25–35 lb/hp, brisk sports cars 10–12, supercars 5–7, and top fuel dragsters under 1. Context matters — gearing and traction decide how much of it you can use.
For comparing how a car will actually accelerate, use running weight with driver and fluids; for comparing manufacturer specs, use their published curb weights consistently.
Instant torque from zero rpm and single-speed gearing remove launch and shift losses — the ratio captures peak power, not how early it arrives.
Only loosely: top speed is fought against aerodynamic drag, which grows with the cube of speed. The ratio predicts acceleration far better than top speed.