Free tool · Training
FTP calculator
Short answer
Functional threshold power (FTP) is the highest power you can hold steadily for about an hour on a bike. The usual shortcut is 95% of your average power from a 20-minute all-out effort, so 250 W for 20 minutes gives an FTP of about 238 W, or 3.17 W/kg at 75 kg. Research shows the shortcut is right on average but can be well off for one rider.
Last reviewed 27 October 20261 published sourcesNot medical advice
Reps keeps track of this for you on iPhone, iPad and Apple Watch.
Get Reps freeFTP calculator
Use the average power from a 20-minute all-out effort on a power meter or smart trainer. Body weight is optional and adds watts per kilogram.
Enter your 20-minute average power.
Runs entirely in your browser. Nothing you type is saved or sent anywhere.
| 20-minute power | FTP | W/kg at 60 kg | W/kg at 75 kg | W/kg at 90 kg |
|---|---|---|---|---|
| 150 W | 143 W | 2.38 | 1.90 | 1.58 |
| 200 W | 190 W | 3.17 | 2.53 | 2.11 |
| 250 W | 238 W | 3.96 | 3.17 | 2.64 |
| 300 W | 285 W | 4.75 | 3.80 | 3.17 |
| 350 W | 333 W | 5.54 | 4.43 | 3.69 |
What the research found
FTP is defined as the highest power a cyclist can hold in a quasi-steady state for about 60 minutes, and 95% of a 20-minute time trial is the usual practical estimate. Borszcz and colleagues tested 23 trained male cyclists: on average, the 20-minute estimate, true 60-minute power and the lab-measured anaerobic threshold were within 1 to 5 W of each other, but for individual riders they differed by as much as about 60 W, and time to exhaustion at the 20-minute FTP was 50.9 ± 15.7 minutes (Borszcz et al., 2018).
So use the number to set training intensities and track progress with the same test, rather than as an exact one-hour limit.
Using it in training
Pair power with heart rate using the heart rate zone calculator, and keep the week's total in check with the training load calculator.
Training load without the spreadsheet
Reps shows your weekly training load building in real time from your Apple Watch workouts and flags an overtraining spike about a week early.
Free to download · iPhone, iPad and Apple Watch
Common questions
How do I calculate FTP from a 20-minute test?
Multiply your average power for the 20 minutes by 0.95. The 5% cut allows for the fact that you can hold more power for 20 minutes than for an hour.
Is the 95% rule accurate?
On average, yes: in 23 trained cyclists, 95% of 20-minute power matched 60-minute power within a few watts. For individual riders the two could differ by up to about 60 W, and riders held their 20-minute FTP for 51 minutes on average rather than a full hour.
What is a good FTP in watts per kilogram?
Watts per kilogram is FTP divided by body weight, so riders of different sizes can compare. This page does not rate scores; the most useful comparison is your own result from one test to the next, done the same way.
Sources
Figures on this page were checked against these publications on 27 October 2026.
- Borszcz FK, Tramontin AF, Bossi AH, Carminatti LJ, Costa VP. Functional threshold power in cyclists: validity of the concept and physiological responses. International Journal of Sports Medicine. 2018;39(10):737–742. doi.org/10.1055/s-0044-101546
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