What is FTP and how to calculate it: 20-minute and ramp tests
If you train with power, sooner or later you will run into three letters: FTP. It is the number your zones, your structured workouts and a good part of your training load are built on. Understanding it properly saves you weeks of riding at the wrong intensity.
What FTP is
FTP stands for Functional Threshold Power: the highest average power you could, in theory, sustain for about an hour without blowing up. It is measured in watts and it is very personal: two riders of the same weight can have very different FTPs.
It is not your maximum power or your sprint power. It is a boundary: below it your body can manage fatigue for a long time; above it, fatigue builds up quickly and you eventually have to stop.
Why it matters so much
It defines your zones: every training zone is a percentage of your FTP.
It gives structured workouts meaning: "3×10 minutes at 95%" only works if you know what your 100% is.
It lets you measure load: the effort of each ride is calculated relative to your threshold.
It makes progress visible: gaining 10 W of FTP is an objective improvement, independent of wind or route.
How to calculate it: the 20-minute test
This is the most widespread method. Do it rested, on flat roads or on a trainer, with a calibrated power meter.
Warm up for 20 minutes, including three 1-minute accelerations with recovery.
Ride 5 minutes flat out and recover for 10 easy minutes (optional, but it sets up the main effort better).
Ride 20 minutes at the hardest steady pace you can hold. Do not start too fast.
Cool down for 10 minutes.
Your estimated FTP is 95% of the average power over those 20 minutes. If you average 250 W, your FTP is about 238 W.
The alternative: the ramp test
Shorter and easier to schedule. You start at a low power and increase it one step every minute until you cannot continue. Your estimated FTP is roughly 75% of your best minute. It works well on a smart trainer with automatic resistance, although it tends to favour riders with a big anaerobic capacity.
The zones that come from your FTP
Z1 · Recovery: under 55%.
Z2 · Endurance: 56–75%.
Z3 · Tempo: 76–90%.
Z4 · Threshold: 91–105%.
Z5 · VO2max: 106–120%.
Z6 · Anaerobic capacity: 121–150%.
How often to retest
The usual advice is to retest every 6–8 weeks or at the end of each training block. If a threshold workout repeatedly feels too easy or impossible, that is a good sign to review the value earlier than planned.
Common mistakes
Starting too hard and fading halfway through the test.
Testing while tired after a hard week.
Comparing values from different power meters without considering their calibration.
Using an "aspirational" FTP that does not match your real fitness.
Next step
Once you have your FTP, add it to your Cyklot profile and let your workouts and plans work with your real watts.