Power-to-Weight Ratio Formula
Calculate power-to-weight ratio (W/kg) for cyclists and endurance athletes.
Understand why it predicts climbing performance.
The Formula
PWR = Power / Weight
Power is in watts, weight is in kilograms. The result is expressed in watts per kilogram (W/kg).
Variables
| Symbol | Meaning | Unit |
|---|---|---|
| PWR | Power-to-weight ratio | W/kg |
| Power | Sustained power output (usually FTP) | watts |
| Weight | Athlete body weight | kg |
Example 1
A cyclist has an FTP of 280 W and weighs 70 kg.
PWR = 280 / 70
PWR = 4.0 W/kg — competitive amateur level
Example 2 — Effect of Weight Loss
Same cyclist loses 5 kg, maintaining the same 280 W FTP.
PWR = 280 / 65
PWR = 4.31 W/kg — a meaningful improvement without changing fitness
W/kg Performance Categories (Threshold Power)
| Category | W/kg |
|---|---|
| World-class climber | 6.0+ |
| Professional | 5.0–6.0 |
| Elite amateur | 4.5–5.0 |
| Competitive amateur | 3.5–4.5 |
| Recreational | 2.5–3.5 |
| Beginner | <2.5 |
When to Use It
- Predicting climbing speed and performance
- Comparing athletes across different body weights
- Tracking fitness progress independently of weight fluctuations
- Setting realistic performance targets