Hong Life CalculatorsUnderstanding the cycling FTP and power zones — concept and principle
Functional threshold power (FTP) is the highest average power, in watts, that a cyclist can sustain for roughly an hour. It is the anchor of power-based training: once you know it, every workout can be written as a percentage of FTP. This calculator estimates FTP from a 20-minute all-out test, expresses it per kilogram of body weight and lists the six training zones described by Andrew Coggan.
How it is calculated
- FTP = 20-minute average power × 0.95.
- W/kg = FTP ÷ body weight (kg).
- Zones, as a share of FTP: Z1 active recovery below 55%, Z2 endurance 56–75%, Z3 tempo 76–90%, Z4 lactate threshold 91–105%, Z5 VO2max 106–120%, Z6 anaerobic capacity 121–150%.
Watts are rounded to whole numbers. Coggan also uses a seventh, neuromuscular level for short sprints, which has no meaningful upper limit and is not listed.
The principle
Power you can hold falls as the effort gets longer. A 20-minute test is short enough to perform well and long enough to be mostly aerobic, but it still includes some anaerobic contribution that would not last a full hour. Taking 95% removes that extra. The zones then split the range of intensities into bands that train different systems: low zones build fat use and capillaries, threshold work raises the power you can sustain, and higher zones target maximal oxygen uptake and anaerobic capacity. W/kg matters because climbing speed depends on power relative to weight.
Worked example
20-minute average 250 W, weight 75 kg.
- FTP = 250 × 0.95 = 237.5 → 238 W.
- W/kg = 237.5 ÷ 75 = 3.17.
- Z1: 237.5 × 0.55 = 130.6 → < 131 W.
- Z2: 0.56–0.75 → 133–178 W; Z3: 0.76–0.90 → 181–214 W.
- Z4: 0.91–1.05 → 216–249 W; Z5: 1.06–1.20 → 252–285 W; Z6: 1.21–1.50 → 287–356 W.
| 20-minute test average power (W) | FTP (95%) |
|---|---|
| 62.5 | 59 |
| 125 | 119 |
| 188 | 178 |
| 250 | 238 |
| 312 | 297 |
| 375 | 356 |
| 500 | 475 |
How to read the result
For many recreational riders FTP lies around 2 to 3 W/kg; competitive amateurs often reach about 4, and professional road racers are commonly above 5. At 3.17 W/kg this rider is a fit recreational cyclist. Retest every 6–8 weeks or after a training block, using the same bike, power meter and route, and update the zones so workouts stay at the right intensity.
Common mistakes
- Pacing the test badly; starting too hard and fading gives a low result.
- Testing while tired.
- Mixing up power meters or a smart trainer and an outdoor meter, which can read differently.
- Using the 0.95 factor on a test shorter than 20 minutes.
Frequently asked questions
Do I need a warm-up before the 20-minute test?
Yes. Allen and Coggan's protocol includes a thorough warm-up with short efforts, which helps you produce a true best effort.
Can I estimate FTP without a power meter?
Not directly in watts. You can train by heart rate or perceived effort instead, or use a smart trainer that measures power.
Is a ramp test the same as a 20-minute test?
No. Ramp tests estimate FTP from your peak one-minute power, often using about 75%, and suit some riders better than others.
Sources: Allen H, Coggan A. Training and Racing with a Power Meter. VeloPress.