FTP Calculator
Turns a 20-minute test into an FTP estimate, power zones and watts per kilogram.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
FTP = 20-minute power × 0.95 W/kg = FTP ÷ rider weight
FTP is the power you can hold for about an hour. The 5% taken off allows for 20 minutes being shorter than that.
What to watch out for
The 95% rule and the seven zones are from Hunter Allen and Andrew Coggan, in Training and Racing with a Power Meter. Warm up well and hold the test at a steady, all-out effort. A start that is too fast gives a low result.
The 95% is an average. Riders with a strong sprint or little endurance can have an hour power well below it, so use a true long effort to check. Zone 7 has no upper limit, so it is shown as a floor.
Frequently Asked Questions
What is the FTP from a 250 W test?
237.5 W at 95%.
What is that in W/kg for a 75 kg rider?
3.17 W/kg.
What power is zone 2 for a 250 W test?
About 133–178 W.