Heart Rate Zones Calculator

Heart rate zones turn a maximum heart rate into target ranges. The tool uses the moderate-intensity band from the American College of Sports Medicine, as cited in a 2025 study, and it shows plain percentages for the rest. If you add a resting rate, it also uses the Karvonen method.

Formulas

How it works, step by step

1. First, the calculator estimates your maximum heart rate from your age.
2. Then it takes 64 to 76% of that maximum for the moderate band.
3. If you entered a resting rate, it also applies the Karvonen formula at 40 to 59% of your reserve.
4. Finally, it lists plain percentages from 50 to 90% of your maximum.

Worked example

At age 30 with a resting rate of 60, Tanaka gives a maximum of 187. Moderate effort by percent of maximum runs from 0.64 x 187 = 120 to 0.76 x 187 = 142 beats per minute. By heart rate reserve it runs from 60 + 0.40 x 127 = 111 to 60 + 0.59 x 127 = 135.

Accuracy and limits

A 2025 study in the International Journal of Exercise Science writes the Karvonen formula as target = (maximum - resting) x intensity + resting. It also cites ACSM moderate intensity as 64 to 76% of maximum heart rate or 40 to 59% of heart rate reserve.

The zones inherit the error of the maximum heart rate estimate. The HUNT study found a standard error of 10.8 beats per minute for its equation.

The two methods give different ranges because the reserve method also uses your resting rate.

• The study cites only the moderate band, so vigorous and other named zones go unlabeled.
• A resting rate taken once may differ from your usual rate.
• If you have a heart condition or take medication that changes your heart rate, ask a clinician before you use heart rate targets.

Sources

1. Rugbumrung M, Rukbumrung T, Impanya S, Thurayot A. Effects of aerobic exercise on physical fitness in obesity using Fox vs. Tanaka's maximum heart rate and percentage vs. Karvonen methods. Int J Exerc Sci. 2025;18(8):695-711. Used for: The Fox and Karvonen formulas as written, and the ACSM moderate-intensity percentages.
2. Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001;37(1):153-156. Used for: The 208 minus 0.7 times age equation and its meta-analysis and lab validation.
3. Nes BM, Janszky I, Wisloff U, Stoylen A, Karlsen T. Age-predicted maximal heart rate in healthy subjects: the HUNT fitness study. Scand J Med Sci Sports. 2013;23(6):697-704. Used for: The 211 minus 0.64 times age equation and its standard error of 10.8 beats per minute.

Sources and math last reviewed: November 4, 2026.