Calculators5 min readUpdated: 2026-09-15
What Is Power to Weight Ratio? Automotive HP/Ton & Cycling W/kg
Definition
The power-to-weight ratio is a measure of an engine or athlete's performance, calculated by dividing total power output by total mass.
Detailed Technical Breakdown
Grounded in Newton's second law of motion ($F = ma$), power-to-weight ratio quantifies acceleration capacity and climbing efficiency. In automotive engineering, it is commonly stated in horsepower per US ton (HP/ton) or pounds per horsepower (lbs/HP). In athletic cycling, it is expressed as Functional Threshold Power in Watts divided by body mass in kilograms (W/kg), serving as the universal standard for classifying racing tiers.
Key Technical Specifications
- Formula: PWR = Power / Mass.
- Automotive metric: HP / (Weight_lbs / 2000).
- Cycling metric: FTP_Watts / BodyWeight_kg.
- Dominates climbing velocity on gradients above 6% where gravity exceeds aerodynamic drag.
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