What FTP is
Functional Threshold Power (FTP) is the highest average power a cyclist can hold for about an hour. Andrew Coggan introduced it as a field proxy for the lactate threshold, and every Coggan power zone is a percentage of it.
Power is measured at the pedals, so it does not drift with heat or fatigue like heart rate. A 10-watt error in FTP shifts every zone.
The Coggan seven-zone model
Zone 1 Active Recovery is below 55% of FTP. Zone 2 Endurance is 56–75%, Zone 3 Tempo 76–90%, Zone 4 Threshold 91–105%, Zone 5 VO₂max 106–120%, Zone 6 Anaerobic Capacity 121–150%, and Zone 7 Neuromuscular Power above 150%.
Most volume sits in Zones 1–2. Zones 5–7 last minutes to seconds, so ride them as intervals.
What is Sweet Spot?
Sweet Spot is 88–94% of FTP, between Tempo and Threshold. At 250 W FTP that is 220–235 W. It gives a near-threshold stimulus for less fatigue than riding at FTP. Typical sessions: 2–4 intervals of 8–20 minutes.
How is FTP measured?
The standard field test is a 20-minute maximal time trial. FTP is 95% of the 20-minute average power. An 8-minute protocol takes 90% of the average of two 8-minute efforts. A ramp test estimates FTP as about 75% of one-minute peak power.
Each method gives a slightly different number. Pick one, keep it, and re-test every 4–6 weeks.
FTP vs threshold heart rate
FTP and lactate-threshold heart rate (LTHR) mark the same boundary in different units. Heart rate lags effort by 1–3 minutes and drifts in heat, so power controls short intervals better. Rising heart rate at the same power flags fatigue or dehydration.
The 20-minute FTP field test
Do it rested, on a trainer or flat road, paced like a hard, even time trial.
- 1
Warm up thoroughly
20–30 minutes easy with a few short spin-ups.
- 2
Blow off the top end
5 minutes all-out to flatten the anaerobic contribution, then 10 minutes easy.
- 3
Ride a 20-minute time trial
Hold the highest steady power you can for 20 minutes, no fade. Record the average.
- 4
Take 95% of the average
Enter the 20-minute average and choose the 20-min mode. The calculator applies the 95% factor.
Worked example
For a cyclist with an FTP of 250 W:
| Zone 2, Endurance (56–75%) | 140–188 W |
| Zone 3, Tempo (76–90%) | 190–225 W |
| Zone 4, Threshold (91–105%) | 228–263 W |
| Sweet Spot (88–94%) | 220–235 W |
This rider would have averaged about 263 W (250 ÷ 0.95) in the 20-minute test.
Frequently asked questions
What is a good FTP?
A good FTP is judged in watts per kilogram. A recreational cyclist sits near 2.5–3.0 W/kg, a strong amateur around 3.5–4.0 W/kg, and elite road professionals exceed 5.5 W/kg at threshold.
How do I test my FTP?
Test FTP with a 20-minute maximal time trial after a warm-up and a 5-minute blow-off effort. FTP is 95% of the 20-minute average power. Alternatives: an 8-minute protocol (90% of average) or a ramp test (about 75% of one-minute peak power).
What is Sweet Spot training?
Sweet Spot training is riding at 88–94% of FTP, between Tempo and Threshold. At 250 W FTP that is 220–235 W. It gives a threshold-like stimulus for less fatigue than full FTP work.
How often should I re-test FTP?
Re-test FTP every 4–6 weeks during focused training, or whenever fitness changes noticeably. Use the same protocol each time so the numbers stay comparable.
Is FTP the same as critical power?
FTP and critical power are close but not identical. FTP is the power sustainable for about an hour, from a single test. Critical power is the asymptote of the power-duration curve, from two efforts, paired with W′. They usually land within a few percent.
Sources
- Allen, Coggan & McGregor, Training and Racing with a Power Meter. 3rd ed. (2019). Definition of Functional Threshold Power and the seven-zone power model.
- Allen & Coggan, FTP & Sweet Spot. Definition of Sweet Spot (88–94% FTP) and the 20-min / 8-min / ramp estimation factors.