Enter the average power output of a 20-minute all-out workout/cycle into the calculator to determine your FTP.

FTP Formula

The following formula is used to calculate a functional threshold power:

FTP = .93 * 20AP

  • Where FTP is functional threshold power (watts)
  • 20AP is the average power maintained over a 20 min all-out biking session

It’s important to warm up before performing the 20 min all-out time trial to properly gauge FTP.

FTP Definition

FTP stands for functional threshold power. This term is used in the sport of cycling to describe the average power output a cyclist can maintain over an hour of all-out effort.

Functional threshold power is achieved at between 85-90% of the maximum heart rate. Since an hour-long time trial is mentally and physically exhausting, cyclists use 20 min time trial estimates for determining functional threshold power (FTP).

Example Problem

How to calculate FTP?

  1. First, warm-up for at least 15 minutes.

    This will prime your body for the time trial.

  2. Next, go all out 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.

  3. Finally, calculate the FTP.

    Using the formula above, the FTP is calculated to be:
    FTP = .93 * 20AP
    FTP = .93 * 300 watts
    FTP = 279 watts
    This cyclist should be able to hold around 279 watts of power for an hour-long race.