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Heart rate zones explained: what do zones 1 to 5 mean?
Updated · 5 min read
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Short answer
Zones 1 to 5 run from very light to maximum effort. Zone 2 is 60 to 70% of maximum heart rate or of heart rate reserve: check which your app uses.
Apple Watch, WHOOP and Polar all use five heart rate zones, from the easiest effort in zone 1 to the hardest in zone 5. Apple and Polar set each zone as a percentage of your maximum heart rate, and WHOOP sets it as a percentage of your heart rate reserve: the range between your resting heart rate and your maximum.
The five zones
| Zone | Effort | Polar: % of maximum | WHOOP: % of reserve | WHOOP: what the zone is for |
|---|---|---|---|---|
| 1 | Very light | 50–60% | 40–60% | Active recovery |
| 2 | Light | 60–70% | 60–70% | The aerobic base |
| 3 | Moderate | 70–80% | 70–80% | Aerobic exercise |
| 4 | Hard | 80–90% | 80–90% | Anaerobic exercise |
| 5 | Maximum | 90–100% | 90–100% | Very high-intensity anaerobic exercise |
The effort names are Polar's. Apple's help page gives no percentage for each zone, so the table has no Apple Watch column.
The American Heart Association uses two broader bands: about 50 to 70% of maximum heart rate for moderate-intensity activity, and about 70 to 85% for vigorous activity. Sources use the word "moderate" for different bands: Polar's table names zone 3 (70 to 80%) Moderate, but Polar's text calls zone 2 (60 to 70%) moderate-intensity.
How your maximum heart rate is set
- The estimate
The American Heart Association and Polar both give 220 minus your age as the simple estimate. For a 40-year-old, that is 180 bpm (beats per minute).
- Its limits
Polar says the formula is not perfectly accurate for all people, especially people who have been fit for many years and older people. Polar says the most accurate way is to have your maximum measured in a laboratory, most often with a maximal treadmill or bicycle stress test.
- On WHOOP
WHOOP estimates your maximum from your age at first, then refines it from your workouts. You can also replace the estimate with a lab-tested maximum in the WHOOP app.
- Medication
The American Heart Association says some medications may lower your maximum heart rate and your target zone. If you take medication, it suggests that you ask your healthcare professional what your heart rate should be.
Why one workout can land in two zones
WHOOP's method is often called the Karvonen formula: target heart rate = ((maximum − resting) × % intensity) + resting. Take a 40-year-old with an estimated maximum of 180 bpm and, as an example, a resting heart rate of 60 bpm.
- Polar's method
Zone 2 is 60 to 70% of 180 bpm: 108 to 126 bpm.
- WHOOP's method
The reserve is 180 minus 60, or 120 beats. Zone 2 is 60 bpm plus 60 to 70% of 120: 132 to 144 bpm.
So a workout at 135 bpm is zone 3 on Polar's method and zone 2 on WHOOP's. WHOOP says its zones shift up as your resting heart rate drops, while zones from your maximum alone stay where they are. If you switch WHOOP to a percentage of maximum, it sets your zones from your maximum heart rate alone, as Polar's default zones do.
See your zones on Apple Watch
- Open the Workout app on your Apple Watch.
- Start a cardio-focused workout, such as an outdoor run.
- Turn the Digital Crown to the Heart Rate Zone view. It shows your zone, your heart rate, your time in the zone and your average heart rate.
- After the workout, open the Fitness app on your iPhone.
- Tap Sessions, then tap the workout.
- Tap Show More next to Heart Rate. A graph shows the estimated time in each zone.
Change your zones on Apple Watch
- Open the Settings app on your Apple Watch.
- Go to Workout then Heart Rate Zones.
Step 2
Where to tap
- Workout
- Heart Rate Zones
- Tap Manual. Manual lets you replace the zones Apple calculates from your health data with your own limits.
- Tap zone 2, 3 or 4.
- Enter the lower and upper limits.
On iPhone, the same setting is in the Apple Watch app: tap My Watch, then go to Workout then Heart Rate Zones.
Change your zones in Polar Flow
- Open the Polar Flow app on your phone.
- Go to the main menu.
- Choose Sport profiles.
- Choose a sport and tap Edit.
- Under Heart rate zone settings, choose Custom. Custom lets you change all the limits. Default keeps the limits that Polar calculates from your maximum heart rate.
- Change the limits.
- Tap Done.
- Sync the settings to your Polar device.
The options depend on your watch, and Polar lists them for each model.
Change your zones in the WHOOP app
- Open the WHOOP app.
- Go to More then App Settings then Activity Settings then Heart Rate Settings.
Step 2
Where to tap
- More
- App Settings
- Activity Settings
- Heart Rate Settings
- Check your zone limits. This screen shows your current cutoffs in bpm for each zone.
- To change the method, switch from heart rate reserve to a percentage of maximum.
- To set your own limits, set custom zones.
To choose a method, see "Why one workout can land in two zones".
If your zones look wrong
- No zones on Apple Watch
Apple calculates zones only after you enter your date of birth in the Health app. On iPhone, open the Health app and tap Summary. Tap your picture or initials, then tap Health Details. Tap Edit, then tap the date of birth field. Enter your date of birth.
- Zones feel too easy or too hard
The estimate of your maximum heart rate may not fit you. See "How your maximum heart rate is set". Set your own limits as in the "Change your zones" sections.
- Old WHOOP workouts keep the old zones
WHOOP does not recalculate past activities, so only new workouts use your new zones.
- Two devices put one workout in different zones
They may use different methods or a different maximum heart rate. See "Why one workout can land in two zones".
Questions
What is zone 2 heart rate?
Polar says zone 2 should feel no harder than brisk walking. Its bpm range depends on your maximum heart rate, and on WHOOP on your resting heart rate too.
Are heart rate zones the same for everyone?
No. Polar gives an example where zone 2 is 120 to 140 bpm for one person and 108 to 126 bpm for another, at the same effort.
Which zone should I train in?
Polar suggests workouts in all five zones, and says that ideally 80% of endurance training is in zones 1 and 2. If you are just starting out, the American Heart Association suggests the lower end, about 50% of maximum, and building up from there.
Sources
- 1View Heart Rate Zones on Apple Watch, Apple Supportsupport.apple.com (opens in a new tab)
- 2Fill out your Health Details in Health on iPhone, Apple Supportsupport.apple.com (opens in a new tab)
- 3Target Heart Rates Chart, American Heart Associationheart.org (opens in a new tab)
- 4Heart Rate Zones, Polarpolar.com (opens in a new tab)
- 5How To Calculate Your Maximum Heart Rate, Polarpolar.com (opens in a new tab)
- 6How can I edit sport profiles and training views in Polar Flow?, Polar Supportsupport.polar.com (opens in a new tab)
- 7Why WHOOP Uses Heart Rate Reserve, Not Max Heart Rate, WHOOPwhoop.com (opens in a new tab)