FTP stands for Functional Threshold Power. It's the highest average power you can sustain for about an hour. Every training zone, every workout intensity, and every measure of training stress is built from this one number.
If you don't know your FTP, your training zones are guesses. And guessing doesn't work.
Why this number matters so much
FTP approximates your lactate threshold. Below it, you can ride for hours. Above it, the clock starts and fatigue stacks fast.
Once you know your FTP, you can:
- Set accurate power zones calibrated to your actual physiology
- Measure workout intensity objectively (not "this felt hard")
- Track fitness changes over months and years
- Compare yourself to other riders as watts per kilogram
- Calculate training stress for every ride
How to test it
Three protocols. Pick whichever you hate least.
20-minute test. Go as hard as you can sustain for 20 minutes. Multiply your average power by 0.95. If you average 250W, your FTP is roughly 237W. This is the most popular test because riding at threshold for a full hour is miserable and almost impossible to pace.
Ramp test. Start easy, increase by 20W every minute until you crack. Take your best 1-minute power and multiply by 0.75. Quick and easy to execute, but it can overestimate FTP if you have a strong sprint.
8-minute test. Two 8-minute all-out efforts with 10 minutes of recovery between them. Average both efforts, multiply by 0.90.
Pacing tip: The most common mistake in the 20-minute test is going out too hard. If you're dying by minute 8, you blew the pacing. The first 5 minutes should feel controlled, almost comfortable. The suffering comes later.
How often: Every 6-8 weeks. FTP doesn't change week to week, and testing more frequently just interrupts your training.
FTP in context (watts per kilogram)
Raw watts matter, but watts per kilogram (W/kg) is what actually predicts performance, especially on hills.
- Beginner: 1.5-2.5 W/kg
- Recreational: 2.5-3.5 W/kg
- Competitive amateur: 3.5-4.5 W/kg
- Cat 1-2 racer: 4.5-5.5 W/kg
- Pro: 5.5-7.0+ W/kg
A 75 kg rider with a 300W FTP sits at 4.0 W/kg. That's strong competitive amateur territory. The same 300W on a 90 kg rider is 3.3 W/kg, which is solid recreational fitness.
How zones are built from FTP
The standard Coggan model uses 7 zones, each a percentage of FTP. Zone 2 (endurance) is 56-75%. Zone 4 (threshold) is 91-105%. Zone 5 (VO2max) is 106-120%. And so on. When your workout says "20 minutes at Zone 4," your FTP is what turns that into an actual wattage target.
Common mistakes
Testing on tired legs. Always test after a rest day. Testing after a hard training week will lowball your FTP, and then all your zones are set too easy. You'll be undertraining for weeks without knowing it.
Never updating zones. If your FTP improved from 220 to 240 and you're still training off the old number, your Zone 4 intervals are actually Zone 3. You're not getting the stimulus you think you're getting.
Treating FTP as everything. FTP tells you about your threshold. It says nothing about your sprint, your 5-minute power, or your ability to ride for 6 hours. It's one number, not the whole picture. But it's the most important single number to have.
If you want to build yours up, check out How to Build Your FTP.