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Heart rate zone calculator (Karvonen)

Short answer

The Karvonen method sets training zones from your heart rate reserve: maximum heart rate minus resting heart rate. Target = resting HR + intensity × reserve. The American College of Sports Medicine calls 40–59% of reserve moderate and 60–89% vigorous. For a 35-year-old with a resting heart rate of 60 and a predicted maximum of 184 bpm, moderate is 110–133 bpm.

Last reviewed 26 October 20263 published sourcesNot medical advice

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Heart rate zone calculator

Karvonen zones from your resting and maximum heart rate.

years
bpm
bpm

Optional. Leave blank to predict it from your age (208 − 0.7 × age).

Enter your age and resting heart rate to see your zones.

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How the zones are calculated

The calculator uses Karvonen's heart rate reserve method (Karvonen et al., 1957): target heart rate = resting heart rate + intensity × (maximum heart rate − resting heart rate).

The intensity bands come from the American College of Sports Medicine's 2011 position stand: light is 30–39% of heart rate reserve, moderate 40–59%, vigorous 60–89% and near-maximal 90% or more (Garber et al., 2011 (ACSM)). If you don't know your maximum, the calculator can predict it with Tanaka's 208 − 0.7 × age (Tanaka et al., 2001).

Moderate and vigorous zones by age and resting heart rate (bpm)
Age · resting HRPredicted maxModerate 40–59%Vigorous 60–89%
25 · 60 bpm191112–138139–177
35 · 60 bpm184110–133134–171
45 · 65 bpm177110–131132–165
55 · 65 bpm170107–127128–159
65 · 70 bpm163107–125126–153
Maximum predicted with 208 − 0.7 × age (Tanaka et al., 2001); zones by the Karvonen method, rounded to whole beats.

Getting better inputs

Measure resting heart rate first thing in the morning before you get up, or use the resting heart rate your watch reports. Compare yours with people your age in the resting heart rate chart.

Predicted maximums can be 10 bpm or more off for an individual. If your watch regularly records a higher peak in all-out efforts, use that instead. The max heart rate calculator compares four formulas.

Your resting heart rate, already measured

Reps reads the resting heart rate your Apple Watch records every day and shows its trend, so the number behind your zones stays current.

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Common questions

How do I calculate heart rate zones?

Subtract your resting heart rate from your maximum to get your heart rate reserve. Multiply the reserve by the intensity you want and add your resting heart rate back. At 60% intensity with a resting rate of 60 and a maximum of 180, that is 60 + 0.6 × 120 = 132 bpm.

Why use heart rate reserve instead of a percentage of max?

Heart rate reserve accounts for your resting heart rate, so two people with the same maximum but different fitness get different zones. The ACSM position stand lists intensity ranges for both methods; this calculator uses heart rate reserve.

What zone is best for fat burning or endurance?

No zone is magic. The ACSM recommends at least 30 minutes of moderate exercise on five or more days a week, or 20 minutes of vigorous exercise on three or more days, or a mix of the two, for adults. Most endurance plans spend most of their time at moderate intensity and a smaller share at vigorous.

Sources

Figures on this page were checked against these publications on 26 October 2026.

  1. Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae. 1957;35(3):307–315. pubmed.ncbi.nlm.nih.gov/13470504/
  2. Garber CE, Blissmer B, Deschenes MR, Franklin BA, Lamonte MJ, Lee IM, Nieman DC, Swain DP. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: guidance for prescribing exercise. Medicine & Science in Sports & Exercise. 2011;43(7):1334–1359. doi.org/10.1249/MSS.0b013e318213fefb
  3. Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology. 2001;37(1):153–156. doi.org/10.1016/S0735-1097(00)01054-8

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