Cycling FTP calculator: threshold, power zones and W/kg
FTP (Functional Threshold Power) is calculated like this: FTP = 95% of your average power over an all-out 20-minute test. Enter your power and your weight, and the tool gives you your FTP, your 7 Allen and Coggan power zones and your watts per kilo.
Fill in the fields to see the result.
How to use it
- Warm up well (20 minutes, building gradually, with a few short accelerations), then ride 20 minutes all out, as steadily as possible.
- Note the average power for those 20 minutes on your power meter or indoor trainer.
- Enter that power and your weight (in kg or in pounds).
- Read your FTP, your watts per kilo and your 7 zones, in watts.
The method
FTP is the power you can hold for about an hour. Riding all out for an hour is hard to do alone, so Hunter Allen and Andrew Coggan proposed a shorter test in “Training and Racing with a Power Meter” (first edition in 2006, third in 2019 with Stephen McGregor): 20 minutes all out, of which you keep 95%. The 5% taken off stands for the part of the effort you can hold for 20 minutes but not for an hour.
From FTP, the book defines 7 zones: Z1 active recovery up to 55%, Z2 endurance from 56 to 75%, Z3 tempo from 76 to 90%, Z4 threshold from 91 to 105%, Z5 VO2max from 106 to 120%, Z6 anaerobic capacity from 121 to 150%, and Z7 sprint above 150%. Watts per kilo (FTP divided by your weight) let you compare riders of different builds, especially on climbs.
An example
You average 250 W over your 20-minute test. Your FTP is 0.95 x 250 = 237.5 W, or about 238 W. At 70 kg, that's 3.39 W/kg. Your zones: Z1 up to 131 W, Z2 from 133 to 178 W, Z3 from 181 to 214 W, Z4 from 216 to 249 W, Z5 from 252 to 285 W, Z6 from 287 to 356 W, Z7 above 359 W.
Limitations
The 95% factor is an average, not a law. Borszcz et al. (2018) found that trained cyclists held the FTP estimated by the 20-minute test for about 51 minutes on average, with big differences from one rider to another, and limits of agreement of about 40 W around the threshold measured in the lab: a 20-minute FTP doesn't replace a real hour for any given person. A poorly paced test (starting too fast, warm-up too short) or one done on a different bike (indoor trainer versus road) also changes the result. Finally, two different power meters can show a few watts' difference. If you have a known heart condition or you're coming back after a long break, talk to a doctor before an all-out test.
Frequently asked questions
How do you calculate your FTP?
The most common method: a 20-minute all-out test after a good warm-up, then 95% of the average power. 250 W over 20 minutes gives an FTP of about 238 W.
What's a good FTP in watts per kilo?
It all depends on your age, sex and training. Compare yourself mostly with yourself: what matters is that your FTP improves from one test to the next, under the same conditions.
Can you do the FTP test on an indoor trainer?
Yes, it's even easier for riding steadily. But many cyclists push a bit less hard indoors: always do your tests in the same place so you can compare them.
How often should you redo an FTP test?
About every 4 to 8 weeks, or at the end of a training block. If your threshold workouts start feeling easy, your zones are probably too low.
What's the difference between FTP and VO2max?
FTP is the power you hold for about an hour. VO2max is your maximum oxygen uptake, reached during efforts of a few minutes, which are much more intense.
Sources
- Allen H., Coggan A.R., McGregor S. (2019). Training and Racing with a Power Meter, 3rd ed. VeloPress.
- Borszcz F.K., Tramontin A.F., Bossi A.H., Carminatti L.J., Costa V.P. (2018). Functional Threshold Power in Cyclists: Validity of the Concept and Physiological Responses. International Journal of Sports Medicine, 39(10), 737-742.
What if ELYO worked it out for you?
ELYO reads the rides recorded by your watch or bike computer, works out your zones and your training load from your real power, and adjusts your plan as your fitness changes.