FTP, or functional threshold power, is the highest power you can hold in a roughly steady state for about an hour, measured in watts. It’s the number most power-based training is built on: your zones, your interval targets and your pacing all come from it. Get it right and every workout lands at the intended intensity. Get it wrong and the whole plan drifts.
What FTP actually means
Hunter Allen and Andrew Coggan defined FTP in their 2006 book on training with a power meter. Allen describes it as “the highest power a rider can maintain in a quasi-steady state without fatiguing,” which in practice is the effort you could sustain for about an hour (Allen, 2025).
Two parts of that definition matter. “Quasi-steady state” means a hard effort your body can still balance, not an all-out sprint. “About an hour” is a guide, not a stopwatch rule. Some riders can hold FTP a little longer, others a little less.
FTP is a field estimate of a physiological boundary. Below it, you can ride hard for a long time. Above it, fatigue builds quickly and you’ll need to back off within minutes. That’s why it’s such a useful anchor for training.
Why FTP matters
It sets your training zones
Power zones are expressed as percentages of FTP. If your FTP is 250 watts, a Sweet Spot interval at 88 to 94% of FTP means holding about 220 to 235 watts. Change your FTP and every target moves with it. These are the zones WattAscent uses:
| Zone | % of FTP | What it trains |
|---|---|---|
| Recovery | Below 56% | Easy riding that helps you recover |
| Endurance | 56–75% | Your aerobic base; most of your riding time |
| Tempo | 76–87% | Steady, comfortably hard muscular endurance |
| Sweet Spot | 88–94% | Big aerobic stimulus for the fatigue it costs |
| Threshold | 95–105% | Raises the power you can hold for about an hour |
| VO2max | 106–120% | Maximal aerobic capacity |
| Anaerobic | 121–150% | Short, very hard efforts and surges |
| Sprint | Max efforts | Peak power in efforts under 20 seconds |
For a deeper look at what each zone does, see Cycling Power Zones Explained.
It helps you pace
Knowing your FTP keeps you from blowing up in the first ten minutes of a climb, time trial or long effort. If a climb takes 20 minutes, you know you can ride a little above FTP. If it takes an hour or more, you know to start at or below it.
It shows your progress
Watching FTP rise over a season is one of the clearest signs your training is working. It’s also the base for comparing riders of different sizes, using watts per kilogram (more on that below).
How FTP is measured
There are four common ways to find your FTP. Each asks for a maximal effort, so do them rested. If you have a heart condition or any other health concern, check with your doctor before doing all-out efforts.
| Test | What you do | How FTP is calculated |
|---|---|---|
| 60-minute test | Ride as hard as you can for one hour | Your average power |
| 20-minute test | Ride a 20-minute all-out time trial | Average power × 0.95 |
| 8-minute test | Two 8-minute time trials with 10 minutes of recovery between | Higher (or average) of the two × 0.90 |
| Ramp test | Power steps up every minute until you can’t continue | About 75% of your best 1-minute power |
The 60-minute test
The most direct test is the one in the definition: ride as hard as you can for an hour. It’s also the hardest to do well. Staying focused for an hour is tough, especially indoors, and a pacing mistake early on can ruin the result.
The 20-minute test
The Allen and Coggan protocol includes a structured warm-up and a 5-minute all-out effort before the 20-minute time trial. You multiply the 20-minute average by 0.95, because Allen and Coggan observed that riders can hold about 5% more for 20 minutes than for an hour. The 5-minute effort beforehand takes the edge off, so the 20-minute number isn’t inflated (Allen, 2025).
Allen also notes the 5% adjustment doesn’t suit everyone. Riders with a big anaerobic capacity may need to subtract more, and riders with very little may need to subtract only about 3% (Allen, 2025).
The 8-minute test
Chris Carmichael’s CTS protocol uses two 8-minute time trials separated by 10 minutes of easy spinning. CTS takes the higher of the two averages and multiplies it by 0.90. Some apps average the two efforts before multiplying (Carmichael, 2022). Shorter efforts are easier to pace and less draining than 20 minutes.
The ramp test
A ramp test raises the power target every minute until you can’t hold it. In the CTS version you start at 100 watts and add 20 watts a minute; without a smart trainer to calculate it for you, you multiply the power of your final stage by 0.75 (Carmichael, 2022). TrainerRoad’s ramp test sets FTP at 75% of your highest 1-minute power (TrainerRoad).
Ramp tests are short and hard to pace badly, which makes them popular. The trade-off is that the result depends on your best minute of power. A rider with an unusually strong or weak finishing kick can get an FTP that’s a little off, the same way Allen notes for the 20-minute test.
Indoor test tips
- Use the same bike, trainer and setup each time so results are comparable.
- For time trials on a smart trainer, CTS recommends slope or resistance mode rather than ERG mode (Carmichael, 2022).
- Use a fan and keep the room cool, so conditions are the same each time.
- Don’t test the day after a hard workout.
How accurate is FTP?
FTP is a practical estimate, not a lab measurement. The research is mixed, and it’s worth knowing where the number is strong and where it isn’t.
FTP and lactate steady state
Maximal lactate steady state (MLSS) is the highest power at which blood lactate stays stable. It’s measured in a lab with repeated constant-power rides and blood samples, so it’s a common reference for “threshold.”
One study of 15 trained and well-trained cyclists found FTP (95% of a 20-minute test) was close to MLSS on average: a bias of 1.4%, a typical error of 4.7%, and a strong correlation (r = 0.91). The error was larger in the less-trained group, and the authors concluded FTP is a practical, noninvasive way to estimate MLSS (Borszcz et al., 2019).
Another study of 18 well-trained cyclists found the opposite. FTP was higher than MLSS, which sat at about 93% of FTP. When the riders were retested after seven months of training, their MLSS rose by 12 watts but their FTP didn’t change significantly (Inglis et al., 2020).
FTP and critical power
Critical power (CP) comes from a different idea: plotting your best efforts across several durations and finding the power you could, in theory, sustain without running out of capacity. Some physiologists argue CP is the best marker of the maximal metabolic steady state, better than MLSS (Jones et al., 2019).
In 17 trained cyclists and triathletes, CP and FTP were strongly correlated (r = 0.969) and close on average: 256 watts versus 249 watts. But for individual riders the two differed by anywhere from about 19 watts below to 33 watts above, so the authors said they shouldn’t be used interchangeably (Karsten et al., 2021).
The 20-minute shortcut versus the full hour
A 20-minute test is a shortcut for a 60-minute effort. One study found the two shouldn’t be used interchangeably for an individual rider (Borszcz et al., 2018). In other words, 95% of your 20-minute power is a good estimate for a group, but it may be a few percent off for you.
What this means for you
FTP works well as a training anchor, and it’s close to lab thresholds for many riders. It isn’t perfect. Treat it as a well-informed estimate, use the same method each time, and pay attention to how workouts feel. If threshold intervals are routinely impossible or routinely easy, your FTP is probably off.
FTP and watts per kilogram
Raw FTP favors bigger riders, who usually produce more power. Watts per kilogram (W/kg) evens that out by dividing FTP by body weight. A 75 kg rider with a 250-watt FTP has 3.33 W/kg. A 60 kg rider with a 220-watt FTP has 3.67 W/kg, and will usually climb faster despite the lower FTP.
W/kg matters most on climbs, where you’re lifting your weight against gravity. On flat roads, aerodynamics and raw watts matter more. To see how your number compares, read What Is a Good FTP?.
How often should you update FTP?
Your FTP changes as you train, rest, get sick or take time off. A stale FTP is a common reason training stalls: if it’s too low, workouts are too easy to drive progress; if it’s too high, you’ll fail intervals and pile up fatigue.
The traditional approach is to retest at the start of each training block. TrainerRoad, for example, prompts a ramp test at the start of each block (TrainerRoad, 2021). The downside is that a test costs a training day, and your FTP can drift between tests.
How WattAscent keeps your FTP current
WattAscent’s Adaptive FTP checks your FTP every two weeks without asking for a test day. It looks at your best efforts from WattAscent rides and connected Strava activities over the past six weeks, plus whether you’ve been completing hard indoor workouts. Raises are capped at 6% per check, and FTP only comes down when there’s clear evidence you’ve lost fitness, such as two failed workouts or more than 14 days off.
If you don’t know your FTP yet, WattAscent doesn’t guess: you start with a Ramp Test. Read how Adaptive FTP works for the full rules.
Get started
FTP is the foundation of structured training, but it only helps if it stays current. WattAscent builds your plan around your FTP, checks it every two weeks using the rides you’re already doing, and adjusts your training around your schedule. It’s $99 a year with a 30-day money-back guarantee. Start training.
Frequently asked questions
What is a good FTP for a beginner?
It depends on your weight, age and training history, which is why W/kg is a fairer comparison than raw watts. The most useful benchmark is your own FTP over time. See What Is a Good FTP? for context on typical ranges.
Which FTP test is the most accurate?
A full 60-minute effort matches the definition most directly, but it’s hard to pace and recover from. The 20-minute, 8-minute and ramp tests are practical shortcuts, and each suits some riders better than others. Pick one and use it consistently so your results are comparable.
Is FTP the same as lactate threshold?
Not exactly. FTP is a field estimate that’s often close to lab thresholds like maximal lactate steady state, but studies disagree on how close. One found a typical error of about 5% (Borszcz et al., 2019); another found FTP sat clearly above it (Inglis et al., 2020).
Can I find my FTP without a test?
Yes. Your best efforts from normal rides can be used to estimate FTP, as long as some of them are hard, sustained efforts. That’s how Adaptive FTP works.
How much can FTP improve?
It varies widely with your starting point, training time and consistency. For practical methods, read How to Increase Your FTP.
References
- Allen, H. (2025). FTP test: what it is and how to do it. Favero Electronics. link
- Carmichael, C. (2022, updated 2026). FTP Tests: How to Perform 20-Minute, 8-Minute, and Ramp Tests. CTS (TrainRight). link
- TrainerRoad. How to Test With the Ramp Test. TrainerRoad Support. link
- Borszcz, F. K., Tramontin, A. F., & Costa, V. P. (2019). Is the Functional Threshold Power Interchangeable With the Maximal Lactate Steady State in Trained Cyclists? International Journal of Sports Physiology and Performance, 14(8), 1029–1035. link
- Inglis, E. C., Iannetta, D., Passfield, L., & Murias, J. M. (2020). Maximal Lactate Steady State Versus the 20-Minute Functional Threshold Power Test in Well-Trained Individuals: “Watts” the Big Deal? International Journal of Sports Physiology and Performance, 15(4), 541–547. link
- Jones, A. M., Burnley, M., Black, M. I., Poole, D. C., & Vanhatalo, A. (2019). The maximal metabolic steady state: redefining the “gold standard”. Physiological Reports, 7(10), e14098. link
- Karsten, B., Petrigna, L., Klose, A., Bianco, A., Townsend, N., & Triska, C. (2021). Relationship Between the Critical Power Test and a 20-min Functional Threshold Power Test in Cycling. Frontiers in Physiology, 11. link
- Borszcz, F., Tramontin, A., Bossi, A., Carminatti, L., & Costa, V. (2018). Functional Threshold Power in Cyclists: Validity of the Concept and Physiological Responses. International Journal of Sports Medicine, 39(10), 737–742. link
- TrainerRoad. (2021, updated 2026). How to Increase FTP and Train Endurance. TrainerRoad Blog. link