Target Heart Rate Zones Calculator

Estimate only, not medical advice. These zones are arithmetic on age and, if you supply it, resting heart rate. They are not a stress test, not a diagnosis, and not a training prescription. If you have heart disease, symptoms with exercise, or a clinician's limit on exertion, use that guidance. Stop and get help for chest pain, fainting, or unusual shortness of breath.

How the zones are calculated

Estimated maximum heart rate on this page is 220 minus age, in beats per minute. A 40-year-old is assigned 180. The page accepts ages from just above 0 through 120 and rejects anything outside that. It does not use other published estimates of maximum heart rate. A watch or a lab that uses a different formula will disagree, and the disagreement is expected.

If you leave resting heart rate blank, or the value is not a positive number below that estimated maximum, each zone is a percent of the maximum. The lower edge is the maximum times the low percent, and the upper edge is the maximum times the high percent. Each edge is rounded to the nearest whole beat. The bands are zone 1 at 50 to 60 percent, zone 2 at 60 to 70, zone 3 at 70 to 80, zone 4 at 80 to 90, and zone 5 at 90 to 100. Because the bands share their endpoints, the same rounded beat can appear at the top of one zone and the bottom of the next.

If you enter a resting heart rate greater than zero and lower than the estimated maximum, the page switches to the Karvonen method and shows a note that it did so. Heart-rate reserve is maximum minus resting. A zone edge is resting plus reserve times the same percents as above, again rounded to the nearest beat. In symbols, edge = resting + (maximum − resting) × percent. There is no separate warning when the resting value is ignored. If the Karvonen note is hidden, the zones are percent-of-max.

Worked examples

Example 1: Age 40, no resting heart rate

Maximum = 220 − 40 = 180. Zone 1 is 50 to 60 percent of 180, which rounds to 90–108. Zone 2 is 108–126. Zone 3 is 126–144. Zone 4 is 144–162. Zone 5 is 162–180. The shared edges are the rounding of exact tenths. 60 percent of 180 is 108, so 108 is both the top of zone 1 and the bottom of zone 2.

Example 2: The same age with a resting heart rate of 60

Reserve = 180 − 60 = 120. Zone 1 runs from 60 + 120 × 0.50 = 120 to 60 + 120 × 0.60 = 132. Zone 2 is 132–144. Zone 3 is 144–156. Zone 4 is 156–168. Zone 5 is 168–180. The top of zone 5 is still the estimated maximum. The lower zones sit higher than in example 1, because the reserve method starts from resting instead of from zero. The note under the zones should be visible. If it is not, the resting value was not used.

Example 3: A resting value the page will ignore

Age 40 and a resting entry of 180 or higher is not below the estimated maximum, so Karvonen does not run. You get the percent-of-max bands from example 1, with the note hidden. A resting heart rate at or above the estimated maximum is a sign to recheck the measurement, not a training zone. The page will not invent a negative reserve.

When to use this

Use it to translate an age into a set of beats-per-minute bands before an easy run, a bike session, or a class that calls out zones. It is a planning sketch. It is useful when a plan says "stay in zone 2" and you need a number to glance at on a watch. It is a weak substitute for a lab test, a clinician-supervised stress test, or the zones your own coach built from your recent training.

The labels on the panel are the page's names for those percents: zone 1 as warm-up, zone 2 as easy, zone 3 as aerobic, zone 4 as threshold, zone 5 as max effort. Those names describe common endurance usage. They are not a statement that fat loss only happens in zone 2, or that every sport should be organized into these five bands. Strength work and short interval sports often use effort, loads, and rest in ways this percentage ladder does not capture. Pair an easy aerobic session with a realistic session length from the Time Duration Calculator if you are checking whether the workout fits the day.

Resting heart rate and what the zones are for

A resting heart rate for the Karvonen path is a calm, seated or waking measurement, not a number taken after climbing stairs. Many people count a full minute first thing in the morning, before caffeine. A single hurried count is a noisy input, and because reserve depends on it, a 10-beat error in resting heart rate moves every zone. If you are unsure, leave the field blank and use percent of max, which has one less source of error and a coarser link to your fitness.

Endurance coaches often keep most weekly time at an easy effort and a smaller share at a hard effort. On this page, easy corresponds to zones 1 and 2 and hard corresponds to zones 4 and 5. Some coaches are skeptical of large amounts of zone 3, on the idea that it is strenuous enough to add fatigue and easy enough to skip the benefit of true threshold work. That is a coaching opinion about how to spend a week. This calculator does not build a weekly plan, and it does not know your sport. Use the beats as a scale, then follow a plan that matches your health and your event.

Talk-test language is a cross-check, not a second formula. Easy zones usually allow conversation. Harder zones usually do not. If the watch says zone 2 and you cannot speak a sentence, believe the effort and treat the estimated maximum as off for you. The 220-minus-age starting point is a population shortcut. Individuals sit on either side of it.

Common mistakes

• Entering age in months or a birth year. The field is age in years. 1986 is not an age the formula can use sensibly, and values over 120 are rejected.
• Typing a heart rate you just measured after a workout into the resting field. That number is not a resting heart rate, and it will shift every Karvonen zone up.
• Assuming the hidden note means Karvonen ran. The note appears only when resting heart rate was used. No note means percent of maximum.
• Treating a boundary beat as a violation. The top of one zone and the bottom of the next can be the same rounded number.
• Comparing this max with a watch that uses another formula and calling one of them broken. They are different estimates. This page is 220 minus age only.
• Using zone 5 as a place to spend a long session. The band goes up to the estimated maximum. Sustained time there is an interval, not a base run, for almost everyone.
• Ignoring symptoms because the number is "in zone." The zone is arithmetic. Pain, dizziness, or a clinician's cap overrides it.

Limitations

One age, an optional resting heart rate, 220 minus age, and five fixed percent bands with ordinary rounding. No measured maximum, no heart-rate drift, no heat adjustment, no medication adjustment, and no zones for pregnancy or cardiac rehab. Beta blockers and some other drugs lower heart rate. A zone built from 220 minus age can sit above what is appropriate if you take them. The page does not ask. Wrist-worn optical sensors and chest straps can disagree with a finger count. The calculator does not read a sensor. It only does the arithmetic.

FAQ

Which formula is running, percent of max or Karvonen?

Look for the note under the zones. If it is visible, the edges are resting plus reserve times the percent. If it is hidden, the edges are the estimated maximum times the percent. Leaving resting heart rate empty always takes the second path.

Why do two zones list the same beat?

The bands meet. Zone 1 ends at 60 percent and zone 2 starts at 60 percent, and each edge is rounded on its own. A beat that lands on the boundary is listed twice. Pick the zone you intended. The training effect does not change because a rounding boundary is shared.

Is zone 2 the only fat-burning zone?

The panel uses "fat burn" as a familiar label for the 60 to 70 percent band. Fat is used as fuel across a wide range of efforts, and total work matters. Do not read the label as a claim that other zones burn none. The calculator's job is the beats, not a metabolism model.

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