Heart-rate zone calculator
Estimate cardio zones while keeping the limitations of heart-rate formulas in plain sight.
Estimate cardio training zones
Enter resting heart rate when you have it. A measured max beats an age-only estimate.
| Zone | Range | Feel |
|---|---|---|
| Zone 1 | 120-132 bpm | Very easy |
| Zone 2 | 132-144 bpm | Easy aerobic |
| Zone 3 | 144-156 bpm | Moderate |
| Zone 4 | 156-168 bpm | Hard |
| Zone 5 | 168-180 bpm | Very hard |
Medication, pregnancy, cardiovascular disease, and unusual symptoms can make heart-rate targets the wrong tool.
The useful number, with the asterisks left in
What this number means
Heart-rate zones are intensity bands. They can help you keep easy days easy, place harder work intentionally, and compare sessions over time.
If you enter resting heart rate, this calculator uses heart-rate reserve. If you only enter age, it uses an estimated max heart rate and percent-max zones.
What it does not know
Age-based max heart rate estimates can be wrong for an individual. Heat, caffeine, dehydration, stress, sleep, altitude, and accumulated fatigue can all move heart rate around.
Heart rate also lags behind sudden changes in pace or power, so it is usually better for steady aerobic work than short intervals.
How to use it
Use the zones as guardrails, not commands. Pair them with the talk test and perceived exertion: moderate work feels like you can talk but not sing; vigorous work makes speaking in long sentences difficult.
If you have a lab-tested or field-tested max heart rate, enter it. A measured max is usually more useful than an age-only estimate.
When not to trust it
Do not rely on heart-rate zones if medication changes your heart-rate response unless your clinician has helped you interpret the numbers.
Chest pain, faintness, unusual breathlessness, known cardiovascular disease, pregnancy, or clinical exercise restrictions should move this out of calculator territory and into clinician guidance.
Caveats
- Healthy-adult estimates only; not medical advice.
- Beta-blockers and some other medications can make heart-rate targets misleading.
- Perceived exertion and the talk test are useful cross-checks.
Examples
- A 40-year-old with no measured max gets an estimated max heart rate of 180 bpm.
- With max HR 180 and resting HR 60, Zone 2 by reserve is about 132 to 144 bpm.
Where the method comes from
- CDC. How to Measure Physical Activity Intensity.
- U.S. Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition.
- Jamnick et al. An examination and critique of current methods to determine exercise intensity. Sports Medicine. 2020.