Glossary · Metrics
Power-to-weight ratio (W/kg)
Power-to-weight ratio is the power a cyclist produces divided by their body weight, expressed in watts per kilogram (W/kg). It's the best single predictor of climbing speed, where gravity rather than air resistance is the main force to overcome.
How to calculate it
Divide your power by your weight in kilograms. A rider with an FTP of 250 watts who weighs 70 kg has an FTP of about 3.6 W/kg. The same idea applies to any duration: five-minute W/kg for short climbs, FTP W/kg for long ones.
Where it matters and where it doesn't
Uphill, W/kg dominates. On flat roads, absolute watts and aerodynamics matter more, which is why heavier, powerful riders can excel on flat courses. Chasing weight loss at the expense of fuelling usually costs more power than it saves.