FTP stands for Functional Threshold Power, and it represents the highest power output (measured in watts) you can sustain for approximately one hour. It’s the single most important number in structured cycling training because nearly every workout, training zone, and race pacing strategy is built around it. Think of it as your cycling fitness score: the higher your FTP, the faster you can ride before your body forces you to slow down.
The Physiology Behind FTP
When you pedal harder, your muscles produce lactate as a byproduct. At lower intensities, your body clears lactate about as fast as it builds up. But there’s a tipping point where lactate accumulates faster than you can process it, and fatigue sets in rapidly. FTP is the power output right at that tipping point, the boundary between efforts you can sustain and efforts that will force you to stop relatively soon.
This is why FTP is sometimes called your “threshold” power. Below it, you can ride for a long time. Above it, you’re on a countdown. How long that countdown lasts depends on how far above threshold you push and your fitness level.
How Long You Can Actually Hold FTP
The textbook definition says FTP is your one-hour power, but most cyclists can’t actually hold their FTP for a full 60 minutes. A study published in the Journal of Science and Medicine in Sport found that recreationally trained cyclists reached exhaustion at FTP after a median of just 35 minutes. Trained cyclists lasted about 42 minutes, well-trained riders around 47, and professional-level cyclists held on for roughly 51 minutes.
So while FTP is defined as a one-hour effort, it’s more accurate to think of it as an intensity that’s sustainable for somewhere between 30 and 60 minutes, depending on your fitness and experience.
How FTP Is Tested
Very few people want to ride all-out for a full hour just to find a training number, so shorter tests are used to estimate FTP.
The 20-Minute Test
This is the most common protocol. You ride as hard as you can sustain for 20 minutes, then multiply your average power by 0.95. That 5% reduction accounts for the fact that most people can push slightly harder for 20 minutes than they could for a full hour. For example, if you average 250 watts during the test, your estimated FTP would be 237 watts. A practical tip: break the effort into four 5-minute segments, adjusting your pace slightly based on how your legs feel at each checkpoint rather than going out too hard and fading.
The Ramp Test
A ramp test starts easy and increases the resistance by a fixed amount every minute until you simply can’t keep pedaling. It typically takes 15 to 25 minutes and feels less psychologically demanding because you don’t have to pace yourself. Your FTP is estimated as 75% of the highest one-minute power you hit before stopping. Ramp tests are popular on indoor training platforms because they’re quick and repeatable, though they can over- or underestimate FTP for riders whose strengths lean heavily toward sprinting or endurance.
What FTP Numbers Look Like
Raw watt numbers don’t tell you much on their own because a 90-kilogram rider producing 250 watts has a very different experience than a 60-kilogram rider producing the same. That’s why cyclists use watts per kilogram (W/kg) to compare fitness across body types.
- Novice cyclists: 2.0 to 2.5 W/kg
- Experienced recreational riders: 3.0 to 4.0 W/kg
- Competitive age-group racers: 4.0 to 4.75 W/kg
- Elite amateurs and professionals: 5.0 to 6.0+ W/kg
To calculate yours, divide your FTP in watts by your body weight in kilograms. A 75 kg rider with a 225-watt FTP has a power-to-weight ratio of 3.0 W/kg, placing them solidly in the experienced recreational category.
How FTP Shapes Your Training
Once you know your FTP, it becomes the anchor for everything in a structured training plan. The system most widely used was developed by exercise physiologist Andrew Coggan and breaks effort into seven zones, each defined as a percentage of FTP.
Active recovery rides sit well below 55% of FTP. Endurance rides, the long steady efforts that build your aerobic base, fall in the range of 56 to 75%. Tempo work pushes into 76 to 90%, a pace that feels comfortably hard. Threshold intervals target 91 to 105% of FTP, the zone that most directly improves your FTP itself. VO2 max intervals, the short, very hard repeats that build your ceiling, land at 106 to 120%. Anything above 121% is anaerobic capacity work with no real upper limit, and pure sprints aren’t referenced to FTP at all since they’re all-out by nature.
This percentage-based system means two riders with completely different FTP values can follow the same structured workout. A recovery ride is a recovery ride whether your FTP is 150 watts or 350 watts, because the zones scale to your personal threshold.
Using FTP for Race Pacing
FTP is especially useful for time trials and other steady-state efforts. For a roughly one-hour event on a flat course, the goal is to average right around your FTP. A common pacing strategy is to start slightly below FTP in the first quarter, then gradually build so that you finish the final quarter right at or just above threshold. This negative-split approach helps avoid the mistake of going out too hard and fading badly in the second half.
For longer events, you’d target a lower percentage of FTP. For shorter ones, you can push above it. The key insight is that FTP gives you a concrete number to plan around rather than relying entirely on feel, which is notoriously unreliable in the excitement of race day.
FTP vs. Critical Power
You may also encounter the term Critical Power (CP), which addresses some of FTP’s limitations. FTP is a single number focused on your aerobic capacity. Critical Power uses a mathematical model that produces two values: CP itself (similar to FTP but derived differently) and a second number called W’ (pronounced “W prime”), which represents your finite reserve of energy above threshold, measured in joules.
W’ tells you how much work you can do above your threshold before you’re forced to ease off. A rider with a large W’ can handle repeated surges above threshold, which matters in road races with attacks and climbs. FTP alone can’t capture that. For most recreational cyclists, FTP is more than sufficient as a training tool, but competitive riders increasingly use Critical Power models for a fuller picture of their capabilities.
Getting Accurate Measurements
FTP is only as reliable as the device measuring your power. Dedicated power meters mounted on cranks or pedals are generally the most accurate, while smart trainers measure power at the rear wheel. Because the chain causes friction, smart trainers often read up to 5% lower than a crank-based power meter on the same bike. This difference isn’t a problem as long as you test and train on the same device. Switching between a power meter and a smart trainer without accounting for the offset will throw off your zones.
Retesting every 4 to 8 weeks keeps your zones current as your fitness changes. If your training zones feel too easy or impossibly hard, your FTP number is probably stale.