FTP Calculator (Cycling Power)

Functional Threshold Power is the cornerstone of structured cycling, the number that tells you the right intensity for every workout and keeps you from drifting into overtraining or coasting too easily. This tool derives your FTP from a 20-minute power test and then maps out the training zones built around it. Even with all the data modern bike computers capture, a disciplined FTP test remains a common benchmark for tracking real performance gains.

The math rests on a well-established convention: your FTP is estimated as 95% of the average power you hold during a maximal 20-minute effort. That discount exists because a hard 20-minute push sits slightly above what most riders can sustain for a full hour, the true definition of threshold. With your FTP fixed, each training zone falls out as a percentage of that figure, following Andrew Coggan's power levels: Zone 1 below 55%, Zone 2 56-75%, Zone 3 76-90%, Zone 4 91-105%, Zone 5 106-120% and Zone 6 from 121% (the calculator shows it up to 150%).

Results live or die on the quality of the test. Pacing too cautiously or blowing up in the first few minutes will both throw off the estimate, so aim for an even, genuinely maximal effort from start to finish. Run the test under repeatable conditions, whether that's the same flat stretch of road or your indoor trainer, so one result can be compared against the next. FTP also shifts as your fitness changes, which is why retesting every 4-8 weeks keeps your zones honest.