How to use the calculator
- Choose whether you’re doing a test or already know your FTP. If you know it (from your bike computer, Zwift or a previous test), enter it and skip to step 3.
- Pick the test type and enter the result. Careful: each test asks for a different number. For the 20-minute test, your average power over those 20 minutes. For the ramp test, your best one-minute power. For the 2 x 8, the average of the two efforts.
- Add your weight if you want to see your watts per kilogram.
You get your FTP, your seven zones in watts and your sweet spot. With Save to My Bike, your FTP is available in the climb time and watts per kg calculators.
What FTP is
FTP (functional threshold power) is the highest average power you can sustain for about 60 minutes. It’s a good indicator of your aerobic fitness and, above all, the reference that training zones are built on: “intervals at 95%” only means something if you know what your 100% is.
Few people do an all-out one-hour test: it’s brutal and hard to repeat. That’s why shorter tests are used, with a correction factor applied to the result.
How we calculate it
FTP = test power × factor
| Test | What you do | Number you need | Factor |
|---|---|---|---|
| 20 minutes | 20 min at a steady maximum, after a good warm-up | Average power for the 20 min | × 0.95 |
| Ramp | Power rises every minute until you can’t continue | Best 1-minute power | × 0.75 |
| 2 x 8 minutes | Two all-out 8-min efforts with 10 easy minutes between | Average of the two efforts | × 0.90 |
| 60 minutes | One hour at a steady maximum | Average power for the hour | × 1 |
The 0.95 factor for the 20-minute test was proposed by Hunter Allen and Andrew Coggan, and it’s the most widely used. The 0.75 for the ramp test and 0.90 for the 2 x 8 test are the factors TrainerRoad applies.
From your FTP we calculate Coggan’s seven levels:
| Zone | Name | % of FTP | With a 250 W FTP | What it’s for |
|---|---|---|---|---|
| Z1 | Active recovery | up to 55% | up to 138 W | Easy spinning, recovering between hard days or intervals |
| Z2 | Endurance | 56-75% | 140-188 W | Long rides: the foundation of training |
| Z3 | Tempo | 76-90% | 190-225 W | Brisk pace; you talk in short phrases |
| SS | Sweet spot | 88-94% | 220-235 W | Lots of stimulus with moderate fatigue |
| Z4 | Threshold | 91-105% | 228-263 W | 10-30 min intervals, time-trial pace |
| Z5 | VO₂ max | 106-120% | 265-300 W | Very hard 3-8 min intervals |
| Z6 | Anaerobic capacity | over 121% | over 303 W | Efforts of 30 s to 3 min |
| Z7 | Neuromuscular | maximum | sprint | Sprints and jumps lasting a few seconds |
Coggan deliberately talks about “levels” rather than “zones”: the boundaries aren’t switches but a continuum. Being 5 W above or below doesn’t matter. Zone 7 has no useful percentage: the efforts are so short that all that counts is going all out.
The watts for every zone at FTPs from 150 to 350 W, already calculated, are in the power zones chart. Sweet spot isn’t one of the seven original levels. The 88-94% range is the most quoted; FasCat, which popularized the term, defines it more broadly, from 84 to 97%.
How to do a 20-minute test right
- Rest the day before or ride very easy.
- Warm up for 15-20 minutes, with two or three short accelerations and, if you like, 5 hard minutes followed by 5 easy ones.
- Start a little below what you think you can hold and build over the last 5 minutes. The most common mistake is starting too hard and falling apart halfway.
- Do it the same way every time: same trainer or same stretch of road, same time of day, same fan. That way the results are comparable.
- Many people test a little lower indoors than outside, because of the heat and not being able to shift position. Use your indoor FTP for indoor training.
Common mistakes
- Using the best 20 minutes from any old ride. If it wasn’t all out and steady, it will underestimate your FTP.
- Applying 0.95 to a ramp test. The ramp test uses your best minute and a 0.75 factor. Mix up the numbers and factors and you can be off by more than 50 W.
- Trusting the ramp test if you’re very punchy. Riders with a lot of anaerobic capacity post a very high best minute, so the ramp overestimates their FTP. If threshold intervals feel impossible, try the 20-minute test.
- Training with an old FTP. After a few weeks of training or time off, your zones are no longer the same.
Terms you’ll see on other platforms
Many apps use terms from TrainingPeaks, the platform that spread Coggan’s model. Normalized Power (NP) is a weighted average that gives more weight to power spikes and better reflects the cost of a ride with lots of surges. Other training load metrics combine duration and intensity relative to your FTP. They all depend on your FTP being right.
From watts to watts per kilogram
Your FTP in watts tells you how hard you push. Divided by your weight, in W/kg (watts per kilogram), it tells you how you climb (the levels by weight are in the watts per kg chart). The watts per kg calculator shows which level that puts you at, and the power to speed calculator shows how fast you’d go on the flat in each zone.
Frequently asked questions
What is FTP in cycling?
It stands for functional threshold power: the highest average power you can sustain for about 60 minutes. It's the reference for setting training zones and tracking your progress.
Why do you multiply a 20-minute FTP test by 0.95?
Because you can hold a bit more for 20 minutes than for an hour. Allen and Coggan proposed taking off 5% to estimate one-hour power, and almost every training platform uses that factor.
What is a good FTP for a recreational cyclist?
It depends on body weight, which is why riders talk in W/kg (watts per kilogram). In the classification based on Allen and Coggan, "good" runs from 2.8 to 3.9 W/kg for men and 2.4 to 3.3 W/kg for women. From 5.05 W/kg (men) or 4.30 W/kg (women) it's "superior".
How often should I retest my FTP?
Every 4 to 8 weeks if you train with a plan, or at the start of a new training block. If threshold intervals suddenly feel easy or impossible, your FTP has probably changed.
What is sweet spot training?
It's the band from 88 to 94% of FTP, between tempo and threshold. It gives a lot of endurance stimulus with less fatigue than threshold work, which is why it's so popular when training time is short.