Watts per Kilogram (W/kg)

Power-to-weight ratio — the most important metric for climbing performance in cycling.

watts per kgw/kgpower to weightclimbingperformance

Understanding Watts per Kilogram (W/kg)

Watts per kilogram (W/kg) is the ratio of your power output to your body weight. It's the single most important metric for cycling performance, especially on climbs where gravity is the primary force to overcome. Two riders with the same absolute power will climb at very different speeds if one weighs 30 pounds more.

W/kg contextualizes raw power numbers. A 200W FTP means very different things for a 60kg (132 lb) rider (3.3 W/kg — competitive) versus a 90kg (198 lb) rider (2.2 W/kg — recreational). On flat terrain, absolute watts matter more; on climbs, W/kg dominates.

Improving W/kg can come from either side of the equation: increasing power (training) or decreasing weight (nutrition). Most coaches recommend focusing on power first, as losing weight without adequate fueling degrades training quality. The optimal approach is to build power through structured training and let body composition improve naturally.

Key Facts: Watts per Kilogram (W/kg)

Key facts and insights about watts per kilogram (w/kg) that every endurance athlete should know.

Calculated as

Calculated as: FTP in watts ÷ body weight in kilograms

Recreational cyclist

Recreational cyclist: 2.0–3.0 W/kg; competitive amateur: 3.5–4.5 W/kg; World Tour pro: 5.5–6.5+ W/kg

W/kg is the best predictor of climbing s

W/kg is the best predictor of climbing speed

On flat terrain, absolute power and aero

On flat terrain, absolute power and aerodynamics matter more than W/kg

Pro Tips: Watts per Kilogram (W/kg)

Focus on raising power (the numerator) before trying to lose weight (the denominator)

Track W/kg over time to see true fitness improvement independent of weight fluctuations

For hilly gran fondos and triathlon bike legs, W/kg determines your performance more than anything

Use a power meter and accurate scale to calculate your W/kg regularly

Frequently Asked Questions About Watts per Kilogram (W/kg)

A functional FTP of 2.0–2.5 W/kg is sufficient to complete the 112-mile bike leg within time cutoffs. Competitive age-groupers aim for 3.0–3.5 W/kg. Remember that Ironman bike pacing is conservative (65–75% FTP) to preserve legs for the marathon.

Only if you can do so without compromising training quality. Under-fueling to lose weight impairs recovery, reduces power output, and increases injury risk. The best approach: train consistently, fuel your workouts well, and let body composition improve gradually. Never diet during a hard training block.