Calculate Zone 2 as 60–70% of maximum heart rate under Polar’s five-zone model.
Values are calculated on this page only; they are not sent to or saved on a server.
Which definition of Zone 2 does this page use?
Zone 2 is not defined identically by every device or training system. This calculator uses 60–70% of maximum heart rate in Polar's five-zone model. The resulting range is not a measurement of your individual lactate or ventilatory threshold.
Before comparing it with another app, check the zone system, whether the calculation uses maximum heart rate or heart-rate reserve, and whether the reference is measured or age-predicted. Matching zone numbers do not necessarily mean matching exercise intensity.
Inputs and formula
Under “Maximum-heart-rate basis”, select “Estimate from age (220 − age)” and enter an adult age from 18 to 90 to use 220 − age. If you have an assessed maximum, select “Use a known maximum heart rate” and enter it in bpm. Do not use resting pulse as your maximum heart rate.
Lower limit = maximum × 0.60; upper limit = maximum × 0.70. Values are rounded to the nearest whole bpm. The accepted maximum of 80–230 bpm is an input check, not a clinically certified range of safe exercise intensities.
Worked example at age 40
In age-estimate mode, age 40 gives 220 − 40 = 180 bpm. The lower and upper limits are 180 × 0.60 = 108 and 180 × 0.70 = 126, producing 108–126 bpm. Selecting “Use a known maximum heart rate” and entering an assessed maximum of 190 bpm produces 114–133 bpm.
| Definition | Percentage | Calculated range |
|---|---|---|
| Polar Zone 2 | 60–70% | 108–126 bpm |
| AHA moderate | 50–70% | 90–126 bpm |
| AHA vigorous | 70–85% | 126–153 bpm |
This comparison explains a difference in definitions, not a competition between the ranges. The target heart rate calculator shows the AHA moderate and vigorous ranges.
Check the reference maximum first
An age equation is a rough population estimate and can differ from an individual's actual maximum. If a watch stores a different maximum from the number used here, it can report different zones even with the same percentages.
One peak reading from an ordinary workout is not enough to establish a true maximum. If an assessed maximum is needed, discuss an appropriate test and interpretation with a professional. An unsupervised all-out effort is not required to use this page.
Use breathing and perceived effort as additional information
Notice whether conversation remains comfortable and how your breathing feels relative to usual activity. CDC's talk test is a general aid to judging intensity; it does not measure a lactate threshold or prove an exact individual Zone 2 boundary.
Even on a familiar route, exercise can feel different from one day to another. Record activity type, duration, and perceived effort along with heart rate to give context to the numbers. Staying inside the displayed range should not become an absolute success criterion.
Is Zone 2 guaranteed to burn the most fat?
This tool does not calculate fat oxidation or predict weight loss. Spending time in a particular heart-rate band cannot guarantee a change in body weight. Overall activity, food intake, sustainability, and health circumstances all matter.
Heart rate also cannot reveal glucose level. If you receive diabetes treatment or develop exercise-related symptoms, agree on appropriate glucose monitoring and activity guidance with your clinical team. Being in a zone does not establish that hypoglycemia is impossible.
Situations that need individual guidance
Beta blockers and other heart-rate-altering medicines, heart disease or arrhythmias, pregnancy, and recovery after illness can make general age-based ranges unsuitable. Stop exercise and seek appropriate medical help for chest pain, feeling faint, or unusual severe breathlessness.
Frequently asked questions
Another app says Zone 2 is 70–80%. Which is correct?
Check its zone definition and reference maximum first. This page explicitly uses Polar's 60–70% definition. If you have individually assessed training zones, review their interpretation with the professional who performed the assessment.
Should I keep changing effort to follow every watch reading?
Do not base the entire plan on one instantaneous number. Review device settings, whether a pattern repeats, and how breathing and effort feel. Symptoms take priority over staying inside a numerical range.
Related tools and sources
Target heart rate calculator · Daily energy calculator · All health calculators · 한국어
- Polar official manual: the five heart-rate zones
- AHA: estimated maximum and exercise intensity
- CDC: the talk test
- CDC: physical activity and weight
- AHA: beta blockers and exercise
Prepared and sources checked by Life Choice Note, 26 September 2026. This is general education checked against the cited sources, not independently physician-reviewed guidance or an individual diagnosis, treatment, or exercise prescription. Editorial standards · Terms and disclaimer