Work out functional threshold power instantly with clear inputs, formula shown and shareable results.
FTP is the power you could hold for roughly an hour, and the standard field estimate is 95% of a maximal 20 minute effort. A 260 W twenty-minute average implies a 247 W FTP, which at 72 kg is 3.43 W/kg. Every training zone is then set as a percentage of FTP, which is why the test is repeated every six to eight weeks.
FTP from a 20 minute test
FTP = 0.95 x 20 minute average power
Power to weight
W/kg = FTP / body mass
This is an estimate from population-average equations, not a medical or diagnostic assessment. Individual results vary with genetics, training history and technique. Seek advice from a qualified coach or clinician before making significant changes to training.
Because a 20 minute maximal effort draws on anaerobic capacity that cannot be sustained for an hour. The 5% reduction approximates that contribution.
Around 2.5-3 W/kg for a recreational rider, 3.5-4.5 for a strong club racer, and over 5.5 for a professional at threshold.