What FTP is
Functional threshold power (FTP) is the highest average power, in watts, that you can sustain for roughly an hour. It sits close to your lactate threshold. Because it is easy to measure with a power meter or a smart trainer, it has become the reference for structured cycling training: every training zone is a percentage of FTP.
Estimating FTP from a test
Few riders want to go all-out for a full hour, so shorter tests are scaled down:
- 20-minute test: FTP = 95% of the average power
- 8-minute test: FTP = 90% of the average of the efforts
- Ramp test: FTP ≈ 75% of the best 1-minute power reached before failing
- 60-minute effort: the average power is your FTP
Warm up for 15 to 20 minutes first, and pace the test evenly: starting too hard is the most common mistake.
The seven power zones
| Zone | Name | % of FTP | Typical use |
|---|---|---|---|
| 1 | Active recovery | up to 55% | Easy spins, recovery days |
| 2 | Endurance | 56–75% | Long rides, aerobic base |
| 3 | Tempo | 76–90% | Steady, moderately hard efforts |
| 4 | Threshold | 91–105% | Intervals of 8 to 20 minutes |
| 5 | VO2 max | 106–120% | Intervals of 3 to 8 minutes |
| 6 | Anaerobic capacity | 121–150% | Efforts of 30 seconds to 3 minutes |
| 7 | Neuromuscular | above 150% | Sprints of a few seconds |
Worked example
A 165 lb rider averages 250 W in a 20-minute test.
- FTP = 250 × 0.95 = 238 W.
- Weight: 165 lb = 74.8 kg, so 3.17 W/kg.
- Endurance rides belong between 133 and 178 W.
- Threshold intervals sit at 216 to 249 W, and VO2 max intervals start at 252 W.
Watts per kilogram
FTP alone favors heavier riders, who usually produce more watts. Dividing by body weight gives a fairer picture, especially for climbing:
- Below 2.5 W/kg: recreational
- 2.5 to 3.2 W/kg: fit amateur, regular club rides
- 3.2 to 4 W/kg: strong amateur
- 4 to 5 W/kg: competitive racer
- Above 5 W/kg: elite and professional
These bands are rough and vary by age and sex.
Using your zones
Most training time, often around 80%, should be easy, in zones 1 and 2. Hard sessions in zones 4 and 5 bring gains only if you recover between them. Retest every 6 to 8 weeks: as FTP rises, every zone moves up with it. Indoor and outdoor FTP can differ by a few percent, so keep separate numbers if you train in both settings.