Turn your FTP into seven practical cycling power zones, or classify a measured wattage against the same continuous boundaries.
How the Cycling Power Zones Calculator Works
Power zones turn one threshold value into repeatable workout targets. This calculator generates the familiar seven-band system and can also identify the band containing a specific wattage.
FTP is the anchor. The calculator applies continuous transitions at 55%, 75%, 90%, 105%, 120%, and 150% so every decimal watt has exactly one classification.
Formula and Method
Formula: zone boundary watts = FTP x boundary percentage; effort percentage = power / FTP x 100
Published tables often print neighboring endpoints as whole percentages, such as 56-75% or 76-90%. The implementation uses the underlying transition values without leaving gaps between zones.
Choosing the Right Inputs
Use a current FTP derived from a consistent test or training platform. In classification mode, enter average or target watts from the same power-meter basis as the FTP.
| Zone | Continuous band | Typical emphasis |
|---|---|---|
| Zone 1 | Below 55% | Active recovery |
| Zone 2 | 55% to below 75% | Aerobic endurance |
| Zone 3 | 75% to below 90% | Tempo |
| Zone 4 | 90% to below 105% | Threshold |
| Zone 5 | 105% to below 120% | VO2 max |
| Zone 6 | 120% to below 150% | Anaerobic capacity |
| Zone 7 | 150% and above | Neuromuscular power |
Understanding Your Results
The FTP or classified zone leads. The supporting table shows watt targets for every band and, in classification mode, the exact percentage of FTP.
Zones are workout anchors rather than physiological walls. Short power spikes can sit well above FTP, while long intervals normally require progressively lower relative power.
Worked Example
With FTP set to 250 W, a 200 W effort is 80.0% of FTP and falls in Zone 3. A 310 W effort is 124.0% and falls in Zone 6.
Common Mistakes
Do not combine an indoor FTP with systematically different outdoor power without accounting for the difference, confuse heart-rate zones with power zones, or treat a one-watt boundary as a biological step change.
Assumptions and Limitations
Zone systems and device rounding vary. FTP can change with fatigue, environment, equipment calibration, and testing protocol, so recalculate after a meaningful threshold update.
Sources
TrainingPeaks. Joe Friel’s Quick Guide to Setting Zones, 2012.