Watts Per Kg Calculator — Power-to-Weight With Real Percentiles

The Calculation Is Trivial. The Interpretation Is Not.

W/kg = power (watts) / body mass (kg)

That part takes a moment. The hard part is what the number means, and that is where most W/kg calculators quietly go wrong.

Why There Is No Coggan Table Here

Almost every page on this keyword prints a version of Andrew Coggan’s power-profile chart: six or seven tiers, from Untrained to World Class, at 5 seconds, 1 minute, 5 minutes and FTP. The trouble is that the versions do not agree with each other. One site puts the men’s FTP world-class floor at 5.70 W/kg**; another puts it at **6.40. A third uses entirely different tier names. The original chart is not published anywhere that can be checked against.

A tier label you cannot verify is worse than no label, because it reads as authoritative. So this tool reports a percentile from a dataset that names itself instead.

Where the Percentiles Come From

Cycling Analytics published an analysis of its own users’ power-meter files in 2018, giving W/kg at each percentile for men and women across 5 seconds, 1 minute, 5 minutes, 20 minutes, and FTP estimated as 95% of the 20-minute figure.

Two honest caveats:

• The population is self-selected. These are riders who own power meters, and roughly half of them race. It skews strong against cycling as a whole. A percentile here means "against riders who measure their power", not "against cyclists".
• No sample size is published. The source says only "thousands of people". The tables run to the 99th percentile for men and the 95th for women, so this tool reports "at or above" rather than inventing a figure past the top row.

Even with those caveats, it beats a number nobody can source.

Reading the Shape, Not Just the Size

One W/kg figure cannot describe a rider. Enter two or more durations and the useful thing appears: which duration you rank best in.

Note that this is the duration with your highest *percentile*, not your highest W/kg — everyone’s 5-second number is larger than their FTP number. A sprinter and a time-triallist can share an FTP and still have opposite curves, and the shape is what tells you which races to pick.

Why W/kg and Not Watts

On level ground, absolute watts win: air resistance scales with frontal area, not mass, so a heavier rider pushing 350 W goes faster than a lighter one pushing 300 W. On a climb, gravity dominates and the ratio takes over — which is why VAM and W/kg track each other closely on steep gradients and loosely on shallow ones.

The practical consequence: a 5 W/kg rider at 60 kg and a 5 W/kg rider at 85 kg climb at the same rate but are not the same cyclist. The heavier one has 425 W to spend on the flat and in the wind. Neither number alone describes a rider; both together start to.