Functional Threshold Power Calculator

What is Functional Threshold Power (FTP)?
Functional Threshold Power is the highest mean power (in watts) a rider can sustain for one hour, serving as a proxy for lactate threshold and maximal metabolic steady state.

Why measure FTP?
Knowing your FTP allows precise intensity prescription: workouts expressed as percentages of FTP target distinct physiological adaptations, from active recovery to maximal efforts, ensuring training is both effective and efficient.

Option 1 - Performing your 20‑Minute FTP Test

1. Preparation

   • Be fully rested (avoid high‑intensity efforts 24 h beforehand).

   • Choose a flat, uninterrupted course or a smart trainer (slope/resistance mode).

2. Warm‑Up (15–20 min)

   • 10 min easy pedalling.

   • 5 min at or just below your expected FTP.

   • 1–2 × 1 min hard efforts with equal recoveries.

3. 20 min Maximal Effort

   • Treat it as a race: accelerate to your goal intensity, then aim for an even pace.

   • Do not start too hard (avoid “blowing up” in minutes 5–10).

4. Cool‑Down

   • 10 min easy spinning.

Extracting your 20 min Average Power

• On your head‑unit: mark a lap at the start and end of the 20 min test, then view the lap’s average power metric.

• Or upload your ride file to TrainingPeaks, create a 20 min lap or split, and inspect the Average Power in the lap summary (“Laps & Splits” feature).

Use that 20 min average power (W) in the calculator; it will compute your FTP as 95 % of that value and assign your power zones accordingly.

Option 2 - Performing your 2 × 8 Minute FTP Test

1. Preparation

   • Be fully rested (avoid hard efforts 24 h prior).

   • Choose a flat, quiet road or a smart trainer in slope/resistance mode.

2. Warm‑Up (15–20 min)

   • 10 min easy spinning.

   • 5 min at or just below your expected FTP.

   • 1–2 × 1 min hard efforts with equal recoveries.

3. First 8 Min All‑Out Effort

   • Ride at the highest power you can sustain for the full 8 minutes.

   • Focus solely on pacing this effort—don’t worry about the second interval.

4. Recovery (10 min)

   • Spin easily to clear metabolites and prepare for the repeat effort.

5. Second 8 Min All‑Out Effort

   • Again, push as hard as possible for 8 minutes; expect a slightly lower average power than in the first interval.

6. Cool‑Down

   • 10 min easy spinning to aid recovery.

How this calculator works

1. Enter your 20 min average power (W), or both the average powers for the 2x8min test (W).

2. Calculate FTP as 95 % of that value for the 20min test, or 90% of the mean of the two values for the 2x8min test (the calculator does this automatically).

3. View your FTP (rounded to the nearest watt) and your power zones in both watts and % FTP:

• Easy / Recovery < 55 % FTP (green) 

• Steady Endurance 56–75 % FTP (green) 

• Upper Aerobic 76–90 % FTP (orange) 

• Threshold 91–105 % FTP (red) 

• Above Threshold > 105 % FTP (red) 

Use these zones to structure sessions—for example, Zone 2 for building endurance capacity, Zone 4 for threshold intervals, and occasional Zone 5 efforts to develop maximal power.