FTP Calculator (Free)
Power-duration reference curve (from this estimate, not measured) · orange dot = your test
This is an estimate based on empirical conversion factors, not a measured FTP. The 20-minute test is the most classic and reliable (×0.95); the closer to an hour, the more stable, and the shorter (especially 5 minutes) the more anaerobic capacity distorts it. For a better number, test at a longer duration or repeat for a consistent value.
How each duration converts to FTP
FTP is the power you can hold for about an hour, so any all-out test shorter than that produces power above FTP and needs a discount. The shorter the test, the bigger the discount:
| Test duration | ≈ % of FTP | Factor |
|---|---|---|
| 5 min | ≈ 118% | × 0.85 |
| 8 min | ≈ 111% | × 0.90 |
| 10 min | ≈ 109% | × 0.915 |
| 15 min | ≈ 107% | × 0.935 |
| 20 min | ≈ 105% | × 0.95 |
| 30 min | ≈ 103% | × 0.972 |
| 40 min | ≈ 101% | × 0.99 |
The tool linearly interpolates any duration in range, so 12, 17, or 25 minutes work too. Factors are common empirical values; individuals vary.
How to run a solid test
You need a power meter (head unit, smart trainer, or power pedals). Warm up thoroughly for 15–20 minutes (including a few short openers), pick a road without frequent braking or use a trainer, and ride evenly and all-out — don't blow up early. Take the average power for that duration and enter it. You can also read your best power for each duration directly from the power curve in Strava, Garmin, or intervals.icu.
Power you train for deserves a bike that fits
However high your power, a poor position leaks watts and invites injury. Upload a side-view riding video and Bikefit.AI measures your knee, hip and torso angles and gives adjustment guidance — so your power actually reaches the pedals.
Upload video, start analysis ›FAQ
What is FTP?
Functional Threshold Power — the max average power you can hold for about an hour, the core metric of aerobic endurance.
Which duration is most accurate?
20 minutes is the classic, reliable choice (×0.95); closer to an hour is more stable, 5 minutes least reliable.
Can 5 minutes estimate FTP?
A rough estimate only — 5-minute power is heavily anaerobic and varies a lot between riders. Prefer longer tests.
What W/kg is strong?
Rough male bands: <2.5 beginner, 2.5–3.2 fitness, 3.2–4.0 well-trained, 4.0–4.7 strong amateur, >4.7 near-elite; women ~0.5–0.6 lower. Reference only.
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