Cycling FTP 20-Minute Test Calculator
Convert your best 20-minute average power into an estimated FTP using the standard 95% factor, with watts per kilogram and your training zones.
How it works
FTP ≈ 20-minute average power × 0.95 · W/kg = FTP ÷ body weight
Functional threshold power is the highest power you could hold for roughly an hour, but nobody wants to test for a full hour. The standard shortcut rides an all-out 20-minute effort and takes 95% of that average, because a fresh 20-minute power is about 5% higher than true one-hour power. Expressing FTP as watts per kilogram makes it comparable between riders and is the number that best predicts climbing performance.
Worked example
A rider who averages 260 W for 20 minutes has an estimated FTP of 260 × 0.95 = 247 W. At 70 kg that is 3.5 W/kg, and their threshold zone (91–105% of FTP) runs from about 225 to 259 W.
Frequently asked questions
Why multiply by 0.95?
A 20-minute maximal effort draws on some anaerobic capacity you could not sustain for a full hour, so it overstates one-hour power by roughly 5%. Taking 95% brings the number back to a sustainable threshold. Some riders do a short 5-minute blow-out before the 20-minute test to drain that anaerobic contribution and instead use the full 20-minute average.
How should I pace the 20-minute test?
Warm up thoroughly, then ride the 20 minutes as an even, maximal-but-sustainable effort — resist starting too hard. A slight negative split (a touch faster in the second half) usually yields the best average and a more reliable FTP estimate.
What is a good FTP in watts per kilogram?
Roughly: 2–3 W/kg is a fit recreational rider, 3–4 is a strong club racer, 4–5 is regional-elite, and above 5 approaches professional level. The exact figure depends on how long you can hold it, but W/kg is the fairest quick comparison.
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This calculator is for educational purposes. Double-check important results before acting on them.