This uses the percentage-of-maximum model - zones start at 50, 60, 70, 80 and 90 percent of HRmax. Many other calculators use percentage of lactate threshold instead, which produces different numbers.
Set your real zones once WattLog.PRO lets you store a measured HRmax and edit every zone boundary by hand, then applies them to every ride you record. Age formulas are only a starting point.
Open WattLog.PROTwo different zone models
There are two common ways to build heart rate zones, and they disagree. One expresses zones as a percentage of maximum heart rate; the other uses a percentage of lactate threshold heart rate. This calculator uses the percentage-of-maximum model, with zones starting at 50, 60, 70, 80 and 90 percent, because that is the model the WattLog.PRO app applies to your recorded rides.
If you have seen different boundaries elsewhere, this is almost always why - a threshold-based Zone 4 and a maximum-based Zone 4 are simply not the same thing. Neither is wrong, but mixing them is, so pick one model and stay with it. What matters for training is that the same effort always lands in the same zone.
Getting a maximum worth using
The 220-minus-age formula is a population average with a standard deviation of about 10 to 12 beats. That is wide enough to shift your zones by a full band, so treat the default as a placeholder until you have real data. If you have ever seen a higher figure on a hard climb or in a sprint finish, that observed number beats the formula.
Heart rate also lags effort by 20 to 30 seconds and drifts upward through a long ride as you heat up and dehydrate. That makes it poor for short intervals and excellent for steady endurance work, where the drift itself tells you how well the ride is going. For anything under about three minutes, use power.
Frequently asked questions
Why are these zones different from other calculators?
Because most cycling sites build zones from lactate threshold heart rate, while this one uses percentage of maximum. The same effort lands in a differently numbered zone under each model. Consistency matters more than the choice, so use whichever model your training app uses.
How do I find my true maximum heart rate?
The highest figure you have genuinely seen in a maximal effort - a long climb finished flat out, or a hard sprint at the end of a race. A formal test involves progressive intervals to exhaustion and is best done when healthy and well rested. Never chase a maximum when tired or ill.
My heart rate is higher than usual at the same power. Why?
Cardiac drift. Heat, dehydration, accumulated fatigue, caffeine, stress and illness all raise heart rate at a given power. A persistent 5 to 10 beat elevation across several days is a reliable signal that you need recovery rather than another hard session.