FTP, or Functional Threshold Power, is the highest power output in watts that you can sustain for roughly one hour on the bike. It’s the single most widely used metric in cycling training, serving as the anchor point for setting training zones, tracking fitness over time, and comparing performance between riders. If you’ve ever used a structured training plan, a smart trainer, or an app like Zwift or TrainingPeaks, your workouts were almost certainly built around your FTP.
How FTP Is Measured
The standard FTP test is a 20-minute all-out time trial. You ride as hard as you can sustain for 20 minutes, then multiply your average power by 0.95 (or 95%) to estimate what you could hold for a full hour. So if you average 300 watts for 20 minutes, your estimated FTP would be 285 watts.
The 95% multiplier is a convenient shortcut, but it’s not universal. Coaches have observed that the actual ratio of FTP to 20-minute power varies significantly depending on rider type. A track sprinter with a strong anaerobic engine might have an FTP that’s only 86% of their 20-minute power, because anaerobic capacity inflates their short effort. A time trialist built for steady-state endurance might sit at 96%. Using 95% across the board can overestimate FTP for some riders and underestimate it for others.
A shorter alternative, the ramp test, has become popular on indoor platforms. You start at an easy wattage and increase by a set amount every minute until you can’t continue. The software then estimates your FTP from your peak one-minute power. It’s faster and easier to pace, but it tends to overstate FTP for riders who have a strong anaerobic system relative to their aerobic base. If accuracy matters to you and you have the discipline to pace a 20-minute effort evenly, the longer test is more reliable.
What FTP Actually Represents in Your Body
FTP is a performance metric, not a direct physiological measurement. It approximates the boundary between exercise intensities you can sustain in a steady state and intensities where fatigue accumulates rapidly. Below your FTP, your body can clear lactate (a byproduct of hard effort) roughly as fast as it produces it. Above your FTP, lactate builds faster than your body can process it, and you’re on a countdown to exhaustion.
That said, the physiological basis isn’t as clean as it sounds. Researchers at the National Strength and Conditioning Association compared FTP values to several lab-based lactate measurements in trained cyclists. FTP (averaging 266 watts in their group) correlated strongly with the power at a fixed blood lactate concentration of 4.0 mmol/L (averaging 268 watts), but the agreement between individual riders was loose, with differences ranging from 45 watts below to 51 watts above. Other lactate thresholds, like the traditional lactate threshold (236 watts in the same group), were significantly lower than FTP. The takeaway: FTP is a useful field estimate of your threshold, but it doesn’t map perfectly onto any single lab measurement.
How Long You Can Actually Hold FTP
Despite the “one-hour power” definition, most cyclists cannot hold their FTP for a full 60 minutes. A study published in the Journal of Science and Medicine in Sport tested time to exhaustion at FTP across different performance levels and found a clear pattern. Recreational cyclists lasted a median of 35 minutes. Trained riders held on for about 42 minutes. Well-trained cyclists managed around 47 minutes, and professional-level riders reached roughly 51 minutes.
Even at the professional level, the median was still under an hour. This doesn’t mean FTP is broken as a concept. It means the 95% multiplier from a 20-minute test slightly overestimates true hour power for most people. In practice, this barely matters for training purposes, because your zones are set as percentages of FTP and the relative intensity is what drives adaptation.
FTP vs. Critical Power
You may also encounter Critical Power (CP), a related but distinct concept. Both attempt to define a boundary between sustainable and unsustainable intensity, but they differ in how they’re calculated and what duration they represent.
FTP is estimated from a single time trial (typically 20 minutes at 95%). Critical Power is calculated from a mathematical model that uses multiple efforts at different durations, plotting the relationship between power and time to find the theoretical wattage you could sustain indefinitely. In practice, CP represents an intensity that can be maintained in a steady state for up to about 30 minutes, while FTP targets a 60-minute steady state. CP tends to come out slightly higher than FTP for the same rider, which makes sense given the shorter sustainable duration.
For most recreational and amateur cyclists, FTP is the more practical number. It’s simpler to test and is supported by virtually every training platform. CP is more common in sports science research and among coaches who want a more granular model of the power-duration curve.
What’s a Good FTP?
Raw wattage depends heavily on body size, so cyclists typically express FTP as watts per kilogram of body weight (W/kg). A 75 kg rider with an FTP of 225 watts and a 60 kg rider with an FTP of 180 watts both sit at 3.0 W/kg, and they’d climb at roughly the same speed.
General benchmarks for men: untrained riders typically fall below 2.0 W/kg, while professional racers sustain more than 6.0 W/kg. For women, the range runs from below 1.5 W/kg (untrained) to above 5.5 W/kg (professional). The majority of cyclists using structured training platforms fall between 2.25 and 3.5 W/kg. Getting above 4.0 W/kg puts you in competitive amateur territory, and anything above 5.0 W/kg is exceptional.
These numbers shift with age, training history, and genetics. What matters most is your own trajectory over time. A 10% improvement in your FTP over a training block is meaningful regardless of where you started.
How FTP Shapes Your Training
The real value of FTP is that it turns your training zones into personalized targets rather than vague effort levels. Most systems divide intensity into zones as percentages of FTP:
- Active recovery: below 55% of FTP
- Endurance: 56–75% of FTP
- Tempo: 76–90% of FTP
- Threshold: 91–105% of FTP
- VO2max intervals: 106–120% of FTP
- Anaerobic capacity: above 120% of FTP
If your FTP is 200 watts, an endurance ride means holding 112–150 watts. Threshold intervals mean riding at 182–210 watts. These numbers make workouts precise and repeatable, which is what drives consistent improvement.
When to Retest
Your FTP changes as your fitness changes, so testing once and never again defeats the purpose. Most training plans build in a retest every four to six weeks, typically at the end of a training block. If your zones start feeling too easy (or impossibly hard), that’s a sign your FTP has shifted and your zones need updating.
Consistency matters more than the specific protocol. If you test with a 20-minute effort, keep using a 20-minute effort. If you use a ramp test, stick with the ramp test. Comparing results across different protocols introduces noise that makes it harder to track real progress. Test in similar conditions each time: same time of day, similar rest and nutrition beforehand, and ideally on the same bike or trainer setup.