Cycling FTP calculator
Functional Threshold Power (FTP) is the cornerstone metric of structured cycling training — the highest power you can sustain for about an hour. This calculator estimates it from the most common field test, your best 20-minute average power, and then builds all seven Coggan training zones in watts so you can train at the right intensity for every session.
How it works
A maximal 20-minute effort is slightly harder than your true one-hour power, so the standard correction is:
FTP = 0.95 × (20-minute average power)Each Coggan zone is then a fixed percentage band of FTP — for example Endurance is 56–75% and Threshold is 91–105%. The tool multiplies your FTP by each band’s bounds to give exact wattage ranges. If you enter your body weight it also reports power-to-weight in W/kg, the number that best predicts climbing and racing performance.
The seven Coggan zones and what each targets
| Zone | Name | % FTP | Primary adaptation |
|---|---|---|---|
| 1 | Active Recovery | under 55% | Light spinning, clears lactate |
| 2 | Endurance | 56–75% | Aerobic base, fat oxidation |
| 3 | Tempo | 76–90% | Sustained muscular endurance |
| 4 | Lactate Threshold | 91–105% | Raises FTP directly |
| 5 | VO2 Max | 106–120% | Cardiac output and aerobic ceiling |
| 6 | Anaerobic Capacity | 121–150% | Short sprint power and repeatability |
| 7 | Neuromuscular Power | above 150% | Peak sprint force |
Most structured training plans spend the majority of volume in Zones 1 and 2, with targeted intervals in Zones 4 and 5. Zone 3 is sometimes called the “grey zone” — hard enough to accumulate fatigue but not hard enough to produce the strong adaptation of Zone 4, so many coaches use it sparingly.
How to do the 20-minute test well
The protocol matters as much as the effort. A common approach:
- Warm up for 15 to 20 minutes including a few short (1-minute) openers at Zone 4 or 5 to prime the system without pre-fatiguing.
- Ride 5 minutes very hard (slightly above your expected threshold) about 5 minutes before the main effort. This reduces anaerobic contribution during the 20-minute test.
- Pace the first 5 minutes conservatively. The most common mistake is going out at a power you cannot sustain, fading in the final 5 minutes, and dragging the average down.
- Record and use average power only, not normalised power, for the FTP calculation.
Worked example
A rider averaging 280 W for 20 minutes has an FTP estimate of 0.95 × 280 = 266 W. At 75 kg body weight that is about 3.5 W/kg — solidly in the trained-amateur category. Their Zone 4 band runs from 266 × 0.91 = 242 W to 266 × 1.05 = 279 W. A 2 × 20 minute threshold interval would target the lower half of that range (around 245 to 260 W) to stay sustainable across both efforts.
Re-test every 4 to 6 weeks during a focused training block to keep the zones current. After a rest week, FTP often rises measurably, and zones that were appropriate two months ago may now be too easy to drive adaptation.
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