How to use the heart rate zones calculator
- Enter your Age (years) and Resting heart rate, measured while sitting or lying calmly.
- Choose a Max heart rate formula, or pick "I know my max heart rate" and type it in.
- Under Zone method, pick Heart rate reserve (Karvonen) to scale the zones to your resting rate, or Percent of max heart rate for the simpler version.
- Read the five zones. Each shows a beats-per-minute range, its intensity and how it feels.
How the zones are calculated
Max heart rate comes from your age: 220 minus age (Fox, the formula on the American Heart Association chart), 208 minus 0.7 times age (Tanaka, from 18,712 people), or 207 minus 0.7 times age (Gellish). Karvonen's 1957 method then sets each target as:
Target = resting heart rate + intensity x (max heart rate minus resting heart rate)
Intensity steps through 50%, 60%, 70%, 80%, 90% and 100%. The percent method skips the resting rate and uses intensity x max heart rate. Each zone starts one beat above the last so ranges never overlap. For reference, the AHA calls 50% to 70% of max moderate and 70% to 85% vigorous.
Worked example
With the starting values (age 35, resting 60, 220 minus age, Karvonen) the max is 185 bpm and the reserve is 125 bpm. The zones are Zone 1 123 to 135, Zone 2 136 to 148, Zone 3 149 to 160, Zone 4 161 to 173 and Zone 5 174 to 185 bpm. Zone 2 tops out at 60 + 0.70 x 125 = 147.5, which rounds to 148.
Limits and edge cases
Every age-based formula misses for individuals. A 2020 comparison of nine equations found errors of roughly 11 to 15 bpm against measured max heart rate (Shookster et al.), so cross-check with the talk test: the CDC says you can talk but not sing at moderate effort and manage only a few words at vigorous effort.
The tool accepts ages 10 to 100, resting rates of 30 to 120 bpm and a resting rate at least 20 bpm below max. Medicines such as beta blockers lower heart rate, so ask your clinician. To turn zones into a plan, pair them with the interval timer, the marathon pace calculator and the calorie burn calculator.
Frequently asked questions
What is my max heart rate by age?
By the 220 minus age formula it is 190 at age 30, 180 at 40, 170 at 50 and 160 at 60. The Tanaka formula gives 187, 180, 173 and 166. Both are estimates, and your real max can differ by 10 to 15 bpm.
What heart rate is Zone 2?
Zone 2 is 60% to 70% of your heart rate reserve, or of your max heart rate with the percent method. For age 35 and a resting rate of 60 it is 136 to 148 bpm with Karvonen and 112 to 130 bpm with percent of max. It should feel like an easy pace where you can talk comfortably.
Should I use Karvonen or percent of max heart rate?
Karvonen uses your resting heart rate, so the zones adjust to your fitness, and it is the better choice if you know your resting rate. Percent of max is simpler and needs only a max heart rate. The two give different numbers, so pick one method and stay with it.
How do I find my real max heart rate?
The most reliable way is a graded exercise test supervised by a clinician or exercise physiologist. Until then, use a formula and cross-check it with the talk test. Do not attempt an all-out test on your own if you have a heart condition or are new to hard exercise.
Sources: AHA, Target Heart Rates Chart; Tanaka et al., J Am Coll Cardiol 2001; Shookster et al., Int J Exerc Sci 2020; CDC, Measuring Physical Activity Intensity.