Seven-zone Coggan model: Z1 below 55% of FTP, Z2 to 75%, Z3 to 90%, Z4 to 105%, Z5 to 120%, Z6 to 150%, Z7 above that.
See your zones live while you ride WattLog.PRO colours your power trace by zone in real time and reports how long you actually spent in each one, instead of how long the plan said you would.
Open WattLog.PROWhere the boundaries come from
The seven-zone model expresses every intensity as a percentage of FTP, which makes a workout portable between riders and between seasons. Zone 1 sits below 55 percent and exists to move blood without adding stress. Zone 2 runs to 75 percent and is where aerobic base is built. Zone 3 reaches 90 percent, Zone 4 straddles threshold from 90 to 105 percent, Zone 5 targets VO2max to 120 percent, Zone 6 is anaerobic work to 150 percent, and Zone 7 is everything above - short neuromuscular sprints where the number on the screen barely matters.
The gaps between zones are deliberately fuzzy because physiology does not switch modes at a threshold. What changes across a boundary is which energy system dominates and how long you can keep going. Treat the numbers as the centre of a target rather than a wall, and remember that the boundaries move the moment your FTP changes.
Training with zones
Most of the benefit comes from the two ends. Zone 2 volume builds the aerobic engine that everything else rests on, and it works precisely because it is easy enough to repeat day after day. Zone 4 and Zone 5 work supplies the sharp stimulus, but it is expensive and self-limiting - you can only absorb so much of it before form goes backwards.
The trap is Zone 3. It feels productive, it is hard enough to be satisfying, and it generates real fatigue without the specific adaptation of either neighbour. Riders who drift there tend to plateau while training more. Ride your easy days genuinely easy and your hard days genuinely hard, and let Zone 3 appear when the terrain demands it rather than by default.
Frequently asked questions
Should I use power zones or heart rate zones?
Power for intervals, heart rate for context. Power responds instantly and tells you exactly what you are doing right now, which is what an interval needs. Heart rate lags by 30 seconds or more and drifts with heat and fatigue, but that drift is itself useful information about how the ride is going.
Why do other sites give different zone numbers?
Because they use different zone models. Five-zone, six-zone and seven-zone schemes all exist, and a Zone 3 in one scheme can be a Zone 2 in another. This calculator uses the seven-zone Coggan model throughout, and so does the WattLog.PRO app, so the numbers stay consistent.
Do my zones change if my FTP changes?
Yes, all of them, immediately. Every boundary is a percentage of FTP, so a 10-watt change shifts the whole set. This is why an out-of-date FTP quietly corrupts every workout you ride - the plan asks for sweet spot and your legs deliver threshold.