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About this tool
Watts per kilogram from your FTP and body mass, with rider category bands, climbing VAM and a target-watts breakdown.
Power to weight is functional threshold power in watts divided by body mass in kilograms, and it is the single number that predicts how fast a cyclist climbs. This calculator returns your W/kg, places it on the Coggan power-profile category bands from untrained through to world class, and converts it into vertical ascent metres per hour using the Ferrari VAM relation so you can estimate a real climb time. It also shows the two levers separately: the watts you would need at your current weight to reach a target, and the weight that would reach it at your current FTP.
Open Cycling Power to Weight Calculator on AltFTool — it loads instantly in your browser.
Enter FTP / threshold power (watts) and Body mass (kg), then set the Category table to Men's bands or Women's bands.
Set Climb gradient (%), Climb height gain (m) and a Target power to weight (W/kg) — enter 0 to hide the target.
Read your W/kg with its rider band and Next band up, plus the VAM and climb figures, then press Copy result.
The raw number is placed on published rider bands for men and women, not left uninterpreted.
VAM, road distance, climb duration and average speed for a gradient you choose.
Watts needed versus kilograms needed for the same target W/kg.
For men, roughly 3.1 to 3.7 W/kg at threshold is a keen recreational cyclist, 4.3 and above is a strong club racer, and above 5.7 approaches professional level. The equivalent women's bands sit lower at each level, by about 0.4 to 0.7 W/kg, with the gap narrowing at the lower bands.
Divide your functional threshold power in watts by your body mass in kilograms. A rider with a 250 W FTP weighing 70 kg has 250 divided by 70, which is 3.57 W/kg. Use body mass alone for comparisons, since that is how the published bands are defined.
VAM is vertical ascent metres per hour — how much height you gain in an hour of climbing. It relates to threshold W/kg by VAM equals W/kg multiplied by 100 and by (2 plus gradient divided by 10), so 3.57 W/kg on an 8 percent climb gives about 1,000 vertical metres per hour.
Gaining watts is usually the safer lever, because weight loss can cost power if it comes from muscle or from under-fuelling training. Use the comparison here to see the size of each option, and speak to a coach or a registered dietitian before making large changes to body weight.
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