Power-to-Weight Ratio Calculator
Divide your cycling power by body weight to get watts per kilogram — the number that decides who wins on the climbs — with a rough category guide.
How it works
power-to-weight = power (W) ÷ body weight (kg)
On a climb, gravity scales with your mass, so what matters is not raw watts but watts per kilogram. A heavier rider making more power can still be dropped by a lighter one with a better ratio. The categories here describe sustained threshold (FTP) power — the number you could hold for about an hour; anaerobic and sprint W/kg are much higher and are judged on different scales.
Worked example
A rider producing 250 W of FTP at 70 kg has 250 ÷ 70 = 3.57 W/kg — a strong club-racer figure. Drop to 65 kg at the same power and the ratio climbs to 3.85 W/kg, which is why cyclists chase both more watts and less weight.
Frequently asked questions
Should I enter FTP or my sprint power?
Either works, but the category guide is calibrated to FTP (one-hour) power. A 5-second sprint might be 15–20 W/kg for the same rider, judged against sprint benchmarks, not the numbers shown here.
Is losing weight or gaining watts the faster win?
For most riders both move the ratio, but weight is often the quicker lever early on because it also improves handling and heat. Beyond a healthy racing weight, chase watts — under-fuelling wrecks training.
Why is power-to-weight less important on the flat?
On level ground you fight air resistance, which depends on raw power and aerodynamics, not mass. That is why big time-trial specialists can be dropped on climbs yet dominate a flat course.
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Estimates for general fitness and education — individual results vary with terrain, fitness, technique and measurement error. Not medical advice.