Getting a Rough FTP Reading Without a Power Meter
FTP (Functional Threshold Power) is roughly the maximum power you can hold for about an hour, and it's the reference point cyclists use to set training zones. A power meter gives you the true number, but without one, you can still estimate a rough range using your average heart rate from a 20-minute time trial and your body weight. This calculator compares your test heart rate to your age-estimated max heart rate, and assumes a higher heart rate percentage roughly corresponds to a higher power-to-weight ratio (W/kg).
Why Use Heart Rate Percentage as the Basis
More trained cyclists tend to produce more power at the same heart rate percentage, so how high your heart rate climbed relative to your max during the 20-minute effort is a rough proxy for fitness level. That said, heart rate is affected by fatigue, caffeine, weather, and stress, so results can shift session to session.
If You Need a Precise Number
For serious training design, run an actual 20-minute or ramp test on a power meter or smart trainer to get your real FTP. Use this calculator as a rough gauge before investing in equipment, or as a quick check on your progress over time.
Frequently Asked Questions
No. Heart rate shifts with fatigue, caffeine, and weather, so this calculator only shows a rough trend. For an accurate FTP, run a real 20-minute or ramp test with a power meter.
After a thorough warm-up, ride for 20 minutes at the hardest sustainable pace you can hold, and record your average heart rate. Avoid going out too hard in the first few minutes, and try to keep effort steady all the way through.
FTP is roughly the maximum power you can sustain for about an hour, and it's the reference point for setting training power zones. Knowing your FTP lets you calibrate interval and endurance intensity to your own fitness.