Calculate cycling FTP from a 20-minute, 2×8-minute, ramp, or 60-minute test, with watts per kilogram, sweet spot, and seven power zones.
Safety note: This calculator provides training estimates, not medical advice. Max-effort tests can be risky—consider medical clearance before testing if you have heart/lung disease, chest pain, fainting, uncontrolled blood pressure, are pregnant, are new to vigorous exercise, or have concerning symptoms. Stop immediately and seek medical care if you develop chest pain/pressure, severe shortness of breath, dizziness, or fainting. Test in a controlled setting and include a thorough warm-up and cool-down.
FTP Formula
A common estimate of functional threshold power (FTP) from a 20-minute time trial is:
- Where FTP is functional threshold power (watts)
- 20AP is the average power maintained over a 20-minute maximal time trial (watts)
To estimate FTP from a 20-minute test, multiply its interval-average power by 0.95. The two-8-minute mode follows TrainerRoad: 0.90 times the mean of both interval averages, excluding recovery. CTS instead uses the higher effort; do not interchange protocols. Ramp mode applies the selected multiplier to the best continuous 60-second average, with 0.75 as the default. Protocol adherence and individual results matter.
Follow the complete prescribed protocol, including warm-up, before performing the 20-minute time trial. Seven power levels appear in the calculation details. Z6 has no 150% upper limit, and Z7 is maximal short-sprint work without a fixed FTP percentage. The displayed continuous zone boundaries adapt the approximate published bands.
FTP Definition
FTP stands for functional threshold power. In cycling, it generally refers to the highest power a rider can sustain in a steady (or near steady) effort for about an hour (often roughly 40–70 minutes).
FTP is a training estimate and is not interchangeable with every laboratory threshold measurement. The heart rate you see at FTP can vary widely by individual, conditions, fatigue, and heat, so it isn’t reliably defined by a single percentage of maximum heart rate. Because a full-hour time trial is mentally and physically demanding, many cyclists use shorter test-based estimates (such as a 20-minute test) to approximate FTP.
Example Problem
How to calculate FTP?
- First, warm up for at least 15 minutes.
This will prime your body for the time trial.
- Next, ride as hard as you can sustain for 20 minutes and record your average power output.
For this example, the cyclist performs the time trial and reaches an average of 300 watts.
- Finally, calculate the FTP estimate.
Using the formula above, the FTP is calculated to be:
FTP = 0.95 * 20AP
FTP = 0.95 * 300 watts
FTP = 285 watts
This cyclist may be able to hold around 285 watts for roughly an hour under similar conditions.
