Free tool
FTP calculator
Your FTP from a 20-minute test, a ramp test or a hard ride, with your training zones and watts per kilo. Free, no sign-up, and nothing you type leaves your browser.
In short
FTP, your functional threshold power, is the highest power you can hold for about an hour. To calculate it, ride a 20-minute test and take 95% of your average power, or ride a ramp test and take 75% of the last full minute you completed. A 20-minute average of 250 watts gives an FTP of 238 watts.
Your training zones
| Zone | Share of FTP | At 238 W FTP |
|---|---|---|
| Z1 Active Recovery | up to 55% | up to 130 W |
| Z2 Endurance | 56% to 75% | 131 to 178 W |
| Z3 Tempo | 76% to 90% | 179 to 214 W |
| Sweet Spot | 88% to 94% | 210 to 223 W |
| Z4 Threshold | 91% to 105% | 215 to 249 W |
| Z5 VO2 Max | 106% to 120% | 250 to 285 W |
| Z6 Anaerobic | 121% to 150% | 286 to 357 W |
| Z7 Neuromuscular | over 150% | over 357 W |
The zones WattPlan's workout player uses. Sweet spot sits across the top of tempo and the bottom of threshold.
Train with it
WattPlan builds a plan around your FTP and the days you can ride, sets every session in your zones, and keeps your FTP up to date from your rides.
How FTP is calculated
FTP is the power you can hold for about an hour. Riding flat out for an hour is a hard way to find it, so tests use a shorter effort and scale it to the hour.
20-minute test. You can hold a little more for 20 minutes than for 60, so your FTP is 95% of your 20-minute average. 250 watts for 20 minutes gives 238 watts.
Ramp test. The target goes up every minute until you can't hold it. Your last full minute is well above threshold, so your FTP is 75% of it. A last full minute of 320 watts gives 240 watts. The 75% is for one-minute steps, so use it on a test built that way, and use the last minute you completed, not the one you stopped in.
From a ride. Your best 20 minutes from a hard ride, with the same 95%. It usually reads a little low, because a ride is seldom an even, flat-out 20 minutes. Don't apply the ramp test's 75% to your best minute from an ordinary ride. That minute is mostly anaerobic power, and the answer comes out too high.
These are the formulas the WattPlan app uses for its tests and for the FTP it estimates from your rides, so the calculator and the app give the same number.
How to ride each test on a turbo or a Wattbike
The 20-minute test
Warm up for 20 minutes, building from easy to moderate with a few short builds. Ride 5 minutes at about threshold to open the legs, then 5 minutes very easy. Then ride 20 minutes as hard as you can hold evenly, and cool down for 10. Ride the 20 minutes with the resistance or gears under your control, not in ERG mode, so you choose the power. Start a little below what you think you can hold and build in the second half. It's your average that counts, and a fast start costs more than it gains.
The ramp test
After 5 minutes of easy spinning, WattPlan's ramp starts at 100 watts and adds 20 watts every minute until you can't hold the target, up to a last step of 580 watts. Here ERG mode on a smart trainer helps, because it sets each step for you. Keep pedalling until you can't turn the pedals at the target. Then note the average power of the last minute you completed in full. A ramp is shorter than the 20-minute test and needs no pacing.
From a ride
Look for your best 20 minutes in a ride where you went hard for that long, a long climb or a hard group ride. Most ride apps and head units can show your best 20-minute power. Connect Garmin, Strava or Wahoo and WattPlan reads it from every ride for you.
Using your FTP for training zones
Your FTP sets your training zones, each a share of it. The table in the calculator shows them in watts for your number. Endurance rides sit in zone 2, sweet spot and threshold sessions build the power you can hold, and VO2 Max intervals raise the ceiling above it. The training zones guide explains what each one trains.
Watts per kilo
Your FTP divided by your weight in kilograms. On the flat, raw watts matter most, because most of your power goes into the air. Uphill, most of it goes into lifting you and the bike, so watts per kilo decides your speed. 238 watts at 75 kg is 3.17 watts per kilo.
The calculator doesn't put a level on your number. The classification sport scientists use to grade riders (De Pauw and colleagues, 2013) is built from peak power in a lab ramp test and from VO2max, not from FTP, so a label from it would be wrong for an FTP.
When to retest
At the end of a training block, when sessions start to feel easy at their targets, or after time off the bike. A test is a hard day, so give it the rest you would give a race. WattPlan's plans without an event finish their block with a test when you have a session long enough for one (45 minutes or more), and the app reads your best 20 minutes from every ride. When they point to an FTP 3% or more higher, it asks you to confirm before it changes your zones.
Questions riders ask
How is FTP calculated?
From a test. In a 20-minute test FTP is 95% of your average power, so 250 watts for 20 minutes gives an FTP of 238 watts. In a ramp test it is 75% of the last full minute you completed, so a last minute of 320 watts gives 240 watts. These are the formulas the WattPlan app uses.
Why 95% of 20 minutes?
FTP is the power you can hold for about an hour, and you can hold a little more for 20 minutes than for 60. Taking 5% off the 20-minute average brings it down to the hour. A ramp test ends in a minute well above threshold, so it takes a bigger cut, 25%.
Can I estimate my FTP without doing a test?
Yes, roughly. Take your best 20 minutes from a hard ride, such as a long climb ridden hard, and use the same 95%. It tends to read a little low, because a ride is seldom an even, flat-out 20 minutes. Don't use your best one minute from an ordinary ride as a ramp result. That minute is mostly anaerobic power, and 75% of it overstates FTP.
Can I use an 8-minute test?
This calculator converts the two tests the WattPlan app runs, the 20-minute and the ramp, so its number matches the app's. Shorter tests need a bigger correction from the test to the hour, and we don't publish a factor the app doesn't use. If you have done one, the best 20 minutes of a hard ride is the closer guide.
What is a good FTP?
Compare in watts per kilo, your FTP divided by your weight, because that decides how fast you climb. We don't put a level on the number. The classification sport scientists use (De Pauw and colleagues, 2013) grades riders by peak power in a lab ramp test and by VO2max, not by FTP, so a label from it would mislead.
How often should I test my FTP?
At the end of a training block, when your sessions start to feel easy at their targets, or after time off the bike. In the app you seldom need a separate test. WattPlan reads your best 20 minutes from every ride and, when they point to an FTP 3% or more higher, asks you to confirm before it changes your zones.
Is the calculator free?
Yes, with no sign-up. It runs in your browser and nothing you type is sent anywhere.
More on FTP
Sources
- De Pauw K, Roelands B, Cheung SS, de Geus B, Rietjens G, Meeusen R. Guidelines to classify subject groups in sport-science research. International Journal of Sports Physiology and Performance, 2013, 8(2), 111-122. doi.org/10.1123/ijspp.8.2.111
FTP from a test is an estimate of the power you can hold for about an hour. Nothing you type here is sent anywhere.