Heart Rate Zone Calculator

Estimating maximum heart rate

220 − age (Fox et al., 1971)
208 − 0.7 × age (Tanaka et al., 2001)

The "220 − age" rule is simple but was not derived from rigorous research, and it tends to underestimate max heart rate in older adults. Tanaka and colleagues analyzed 351 studies and confirmed the 208 − 0.7 × age formula in a laboratory study; it is the headline result here. Both give the same answer at age 40 (180 bpm); by age 60, Tanaka gives 166 bpm versus 160.

Two ways to set zones

Percentage of max HR: zone = max HR × percentage. Simple and widely used.

Karvonen (heart rate reserve): uses your resting heart rate, so it adapts to your fitness:

Target = (max HR − resting HR) × intensity + resting HR

Measure resting heart rate first thing in the morning, before getting up, on a few days and average.

The five zones

Using zones in practice

Endurance athletes often spend most training time in zones 1–2, with smaller amounts of hard work. Heart rate lags behind effort at the start of intervals and drifts upward in heat or as you tire, so combine it with perceived effort. Wrist-based monitors can be inaccurate during intervals; chest straps are more reliable.

How to measure resting heart rate

Measure on waking, before getting out of bed or drinking caffeine. Find your pulse on your wrist or neck, count beats for 30 seconds and double it, or use a reliable monitor. Repeat on three to five mornings and average. A rising resting heart rate over several days can signal fatigue, illness or poor sleep.

Finding your true maximum

Because formulas can be off by 10–20 beats per minute, some athletes use field tests — such as a hard 3-minute uphill effort after a thorough warm-up — and take the highest reading. These are strenuous and only suitable for healthy, trained people; a supervised exercise test with a clinician is the safest option, especially if you have risk factors.

Talk test and perceived exertion

You don't need a monitor to train by intensity. During moderate activity you can talk but not sing; during vigorous activity you can say only a few words without pausing for breath. The U.S. Physical Activity Guidelines recommend at least 150 minutes a week of moderate or 75 minutes of vigorous activity for adults, and either measure works for meeting them.

Example weekly plan

A recreational runner doing four sessions a week might do two easy zone 2 runs, one longer zone 2 run, and one session with intervals reaching zone 4. Keeping most time easy builds endurance while limiting fatigue and injury risk.

Worked examples

Example 1: Age 40, no resting HR

Tanaka max = 208 − 28 = 180 bpm. Zone 2 (60–70%) = 108–126 bpm.

Example 2: Age 40, resting HR 60 (Karvonen)

Reserve = 180 − 60 = 120. 70% = 120 × 0.70 + 60 = 144 bpm. Zone 3 (70–80%) = 144–156 bpm.

Example 3: Age 60

Tanaka = 208 − 42 = 166 bpm; 220 − age = 160 bpm.

Limitations

• Formulas predict an average; individual max HR can differ by 10–20 bpm.
• A lab or field max test gives your true max.
• Heat, caffeine, dehydration and stress raise heart rate.

Who should not rely on this calculator

People taking beta-blockers or other heart-rate-lowering medicines, people with heart disease, arrhythmias or a pacemaker, and pregnant people should get personalized intensity guidance from their doctor. Stop exercising and seek care for chest pain, fainting or severe breathlessness.