There is no single zone method that owns the whole category.
Different apps choose different defaults. Some use percent of max heart rate. Some use heart rate reserve. Some let coaches or users set boundaries directly.
Zonas keeps three paths.
Method 1: Karvonen / Heart Rate Reserve
This is the preferred automatic path.
It needs:
- max heart rate
- resting heart rate
The formula:
reserve = HRmax - RHR
target = RHR + intensity x reserveZonas uses these workout-zone bands:
| Zone | HRR band |
|---|---|
| Zone 1 | 50-59% |
| Zone 2 | 60-69% |
| Zone 3 | 70-79% |
| Zone 4 | 80-89% |
| Zone 5 | 90-100% |
Heart rate reserve is a better default when the resting value is real, because it accounts for the space between your resting heart rate and your maximum.
Method 2: Percent Of Max Heart Rate
This is the automatic fallback.
It needs:
- max heart rate
The formula:
target = intensity x HRmaxThe bands are the same 10-point bands:
| Zone | HRmax band |
|---|---|
| Zone 1 | 50-59% |
| Zone 2 | 60-69% |
| Zone 3 | 70-79% |
| Zone 4 | 80-89% |
| Zone 5 | 90-100% |
This is less personal than HRR, but it is still useful when resting heart rate is missing.
Method 3: Custom Boundaries
Custom mode is for people who already know what they want.
Maybe your coach gave you zones. Maybe another platform has zones you want to match. Maybe you tested thresholds and want the app to follow those numbers.
In the current app, custom boundaries are percentages of max heart rate. They override Automatic mode.
How Zonas Chooses
The decision tree is short:
| State | Method |
|---|---|
| Custom mode | Custom percent-HRmax boundaries |
| Automatic + resting heart rate | Karvonen / HRR |
| Automatic without resting heart rate | Percent HRmax |
Zonas does not ask you to pick between scientific modes during setup. The app uses the best available inputs and lets advanced users override the result.
Whole-BPM Ranges
Zonas turns percentages into whole BPM ranges with truncation.
For Zones 1-4, the high end is one beat below the next zone’s low end. Zone 5 ends at max heart rate.
That means zones do not overlap.
If Zone 3 starts at 148, Zone 2 ends at 147.
Why The Labels Stay Simple
The zone labels are:
| Zone | Label |
|---|---|
| 1 | Recovery |
| 2 | Aerobic |
| 3 | Steady |
| 4 | Hard |
| 5 | Peak |
They describe effort without overpromising physiology. Zonas does not claim that a generic zone label can tell you exactly which fuel source you are using or where your lab-tested threshold sits.
Common questions
Which zone method does Zonas prefer?
Automatic mode prefers Karvonen heart rate reserve when resting heart rate exists. That lets the app account for the range between rest and maximum.
What happens if resting heart rate is missing?
Zonas uses percent of max heart rate. It does not estimate resting heart rate just to force the Karvonen method.
Do custom boundaries use Karvonen?
No. In the current app, custom boundaries are percentages of max heart rate. Custom mode exists for users who already have a preferred zone model.
Sources
- View Heart Rate Zones on Apple Watch
Apple Watch offers automatic heart rate zones and manual editing, a useful consumer reference for five-zone UX.
- Age-predicted maximal heart rate revisited
Tanaka max heart rate estimate used by the app when no custom max heart rate is available.
- restingHeartRate
HealthKit exposes resting heart rate samples that Zonas uses for heart rate reserve calculation.