What this calculator does
Get your estimated maximum heart rate and five heart-rate training zones, so you know how hard to work out. Training by heart rate is a simple way to control your effort. Easy days stay easy, hard intervals are hard enough, and you can compare efforts from week to week. Zones are bands of heart rate, each set as a share of your maximum. Most systems use five of them, from very light recovery work up to all-out efforts.
The calculator estimates your maximum heart rate from your age. It can use the classic 220 − age rule or the Tanaka equation, or a maximum you've measured yourself. Then it sets the five zones in one of two ways. One is a straight percentage of your maximum. The other, the Karvonen method, also uses your resting heart rate. Every figure is an estimate, not medical advice. If you have a heart condition, take medicine that affects heart rate, or are starting intense exercise, talk to a doctor first.
Where it's used
Why this math matters outside the classroom:
- Estimated maximum. For a 40-year-old, 220 − 40 gives an estimated maximum heart rate of 180 beats per minute.
- Zone boundaries. Taking 60% and 70% of 180 bpm sets a training zone that runs from 108 to 126 bpm.
- Karvonen method. With a resting rate of 60, adding 70% of the 120 bpm reserve to 60 gives a target of 144 bpm.
- Training plans. Runners plan easy days and hard sessions by zone, then glance at a watch to stay inside each range.
- PE class. Physical education classes have students take their pulse after exercise and compare it with their own zone numbers.
Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.RP.A.3.c, 6.EE.A.2.c. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
How to use it
- Choose how to find your maximum heart rate: 220 − age, the Tanaka equation, or a maximum you already know.
- Enter your age, or your measured maximum.
- Choose percentage of maximum or Karvonen. For Karvonen, enter your resting heart rate.
- Read the zone table, along with the moderate (50–70%) and vigorous (70–85%) ranges.
What the inputs mean
- Maximum heart rate
- Both age formulas describe averages across many people. One person's real maximum often differs from them by 10 beats per minute or more, either way. So if you have a reliably measured maximum, it's the better choice.
- Measured maximum heart rate
- The highest rate you have reliably recorded during an all-out effort.
- Zone method
- Percentage of maximum is the simplest. Karvonen applies the percentages only to the range between your resting and maximum rates. So its zones sit higher, especially for people with a low resting heart rate.
- Resting heart rate
- Take it when you wake up, before getting out of bed, by counting your pulse for a full minute. Averaging a few mornings helps.
Formula and method
Max HR (classic) = 220 − age Max HR (Tanaka) = 208 − 0.7 × age Zone limit (% of max) = intensity × max HR Heart-rate reserve = max HR − resting HR Zone limit (Karvonen) = resting HR + intensity × reserve
HR stands for heart rate, in beats per minute (bpm). Intensity is how hard you're working, as a percent, such as 0.7 for 70%. The five zones use the common boundaries of 50, 60, 70, 80, 90 and 100% intensity.
The Tanaka equation was put forward as a better fit than 220 − age for older adults. The two agree at age 40, where both give 180. At other ages they differ by up to several beats.
The Karvonen method uses your heart-rate reserve, the gap between your resting and maximum rates. Because it starts from your resting rate, the same intensity percent gives a higher target than the percentage-of-maximum method.
Worked example
A 40-year-old with a resting heart rate of 60 bpm uses 220 − age and the Karvonen method.
- Maximum heart rate: 220 − 40 = 180 bpm.
- Heart-rate reserve: 180 − 60 = 120 bpm.
- Zone 1 starts at 60 + 0.5 × 120 = 120 bpm; zone 3 starts at 60 + 0.7 × 120 = 144 bpm.
- The zones are 120–132, 132–144, 144–156, 156–168 and 168–180 bpm.
Result: The estimated maximum is 180 bpm, with a moderate-intensity range of 120–144 bpm and a vigorous range of 144–162 bpm.
Understanding the result
In endurance training, most of the time is usually spent in zones 1 and 2, with smaller amounts in zones 3 to 5. A common guideline is to build up regular moderate activity across the week, and add harder sessions gradually.
Your heart rate takes a little while to catch up at the start of an interval. It also creeps upward during long sessions, especially in the heat. So use zones as a guide, together with how the effort feels.
Your measured heart rate may often be far above or below what the zones predict for an effort. If so, your true maximum is probably different from the estimate.
Assumptions and limitations
- The age formulas are meant for healthy adults and teenagers from 15 years old.
- Zones use fixed boundaries in 10% steps from 50% to 100%.
- Heart rates are rounded to whole beats per minute in the results.
- A maximum heart rate predicted from age can be far off for any one person.
- Medicines such as beta blockers, illness, caffeine, heat, altitude and dehydration all change heart rate.
- Different coaching systems draw the zone boundaries in different places. These are one common set.
- This calculator doesn't check heart health and isn't a substitute for medical advice.
Frequently asked questions
Which is better, 220 − age or the Tanaka formula?
Neither is accurate for everyone. Tanaka tends to fit older adults slightly better, while 220 − age is simpler and more widely quoted. At age 40 they give the same answer.
What is the Karvonen formula?
It sets a target heart rate as your resting rate plus a percentage of your heart-rate reserve (maximum minus resting). Because it takes your resting heart rate into account, it adjusts the zones to your fitness level.
What heart rate counts as moderate intensity?
Moderate intensity is commonly described as about 50–70% of maximum heart rate, and vigorous intensity as about 70–85%. The calculator shows both ranges for your inputs.
How do I find my real maximum heart rate?
The most reliable way is a maximal exercise test, done with medical supervision. Some athletes record a peak during a hard sprint at the end of a race. But an all-out effort isn't advisable without a doctor's go-ahead.
How this calculator is checked
Method: Age-predicted maximum heart rate (220 − age; Tanaka 208 − 0.7 × age); percentage-of-maximum zones; Karvonen heart-rate reserve method. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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