No. It is a simple population estimate and can be well off for a specific individual, real variation between people of the same age reaches tens of beats. Use the result as a starting point, not a hard limit.
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Calculate moderate and vigorous zones with a choice of Fox or Tanaka, plus Karvonen.
Heart-rate zones help guide the intensity of an aerobic workout: to burn fat and build base fitness you stay in the moderate zone, and to gain performance you move up to the vigorous one. The catch is that it all starts from an estimate of maximum heart rate, which can be computed by different models. This calculator lets you choose between Fox (the classic 220 − age) and Tanaka (208 − 0.7 × age) and shows the other method alongside, so you do not mistake an estimate for an exact measurement. If you know your resting HR, you can enable the Karvonen method, which personalizes the zones using heart rate reserve. The 50–70% (moderate) and 70–85% (vigorous) ranges follow the American Heart Association reference.
Fox and Tanaka estimate max HR from age alone, but with different slopes: the classic 220 − age (Fox) tends to underestimate in older people, while 208 − 0.7 × age (Tanaka), derived from a more recent meta-analysis, is generally considered more representative of the population. Neither replaces a real exercise test, because individual variation is large.
Karvonen does not change max HR; it changes how the zones are computed. Instead of applying the percentage straight to max HR, it uses heart rate reserve (max HR − resting HR) and adds the resting HR back. The result is a zone personalized for someone with a lower resting rate (more conditioned) or a higher one.
Example 1, simple method, age 30: by Fox, max HR = 220 − 30 = 190 bpm; the moderate zone (50–70%) runs from 95 to 133 bpm and the vigorous (70–85%) from 133 to 162 bpm. By Tanaka, max HR = 208 − 0.7 × 30 = 187 bpm, shifting the ranges slightly, which is why seeing both methods helps.
Example 2, Karvonen, age 40 with resting HR 60: Fox gives max HR 180, so the reserve is 180 − 60 = 120. The moderate zone is 60 + 0.5 × 120 = 120 bpm up to 60 + 0.7 × 120 = 144 bpm; the vigorous, from 144 up to 60 + 0.85 × 120 = 162 bpm. Notice how including the resting rate raises the floor of the zone versus the simple method.
Beta-blockers and other medications can lower or alter the cardiac response, making formula-based zones unreliable, in those cases a professional's guidance is essential. Chest pain, severe shortness of breath, dizziness or palpitations are signs to stop exercising and seek help, regardless of what the number shows.
The rating of perceived exertion (how hard the effort feels, on a subjective scale) is a good complement to heart rate, especially when the sensor fails or the max-HR method does not represent your profile well. Warm-up, cool-down and gradual progression matter more for safety than hitting an exact bpm.
Paste the code into your HTML and the tool shows up on your page, without J-Kit's navigation and ads. It still runs in the browser of whoever visits your site.
<iframe
src="https://jkit.tools/embed/en-US/target-heart-rate-calculator"
width="100%"
height="600"
style="border:0"
loading="lazy"
title="Target Heart Rate Calculator"
></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
No. It is a simple population estimate and can be well off for a specific individual, real variation between people of the same age reaches tens of beats. Use the result as a starting point, not a hard limit.
Medical notice: if you have a heart condition, symptoms, take medication that changes heart rate, or are starting to exercise, consult a health professional.
| Zone | Tanaka (208 − 0.7 × age) | Karvonen |
|---|---|---|
| Moderate | 92–129 | 125–148 |
| Vigorous | 129–156 | 148–166 |
Fox and Tanaka are different formulas for estimating max HR. The tool uses the selected method to calculate zones and shows the alternative alongside to avoid a false sense of absolute precision.
Fox: 220 − age. Tanaka: 208 − 0.7 × age. Moderate: 50–70%; vigorous: 70–85%. Karvonen uses heart rate reserve when resting HR is provided.
Age and resting heart rate stay in the browser and are not sent to analytics.