Target Heart Rate Zone Calculator

What is a heart rate zone?

A heart rate zone is a band of heartbeats per minute, expressed as a share of your maximum heart rate, that gives you a rough label for how hard your body is working. The same running pace can feel easy on a cool, well-rested morning and punishing on a hot day after a bad night of sleep. Heart rate captures that internal load as a number, which is why many people steer their training by zones instead of by speed or weight alone.

How many zones there are, and what they are called, differs between books, coaches, and watch makers. This calculator uses five bands in steps of ten percentage points, starting at 50 percent. The boundaries are conventions, not physiological switches: nothing special happens in your body at exactly 70 percent versus 69 percent. Treat the labels as a way to organize a training week rather than as precise scientific categories.

Estimating maximum heart rate: 220 minus age and its limits

The most familiar formula is 220 − age. It is easy to remember, but it is a rule of thumb rather than a precisely validated model, and researchers have long pointed out that individual results scatter widely around it. Two people of the same age can differ by several beats per minute, and often by more than ten (figures around plus or minus 10 to 12 bpm are commonly quoted, though the exact spread depends on the study). Genetics, training history, and the type of exercise all play a part.

A frequently cited alternative is 208 − 0.7 × age, published by Tanaka and colleagues in 2001 in the Journal of the American College of Cardiology. It was derived from a meta-analysis of 351 studies (about 18,700 subjects) and checked against laboratory testing of 514 healthy adults, and the authors reported that the older rule tends to underestimate maximum heart rate in older people. As the table shows, the two formulas agree at age 40; below that the classic formula gives the higher number, above it Tanaka gives the higher number. Like the classic formula, Tanaka describes an average, not a prediction for any one person.

The most reliable number is a measured one. A maximal exercise test involves warming up and then raising the intensity every two or three minutes until the heart rate stops climbing. That is demanding, and it can be risky for anyone with cardiovascular risk factors. If you are 40 or older, have a medical condition, or have any symptoms, a supervised exercise stress test is the safe way to find your true maximum. If you already have a measured value, choose "Enter a measured value" in the calculator.

The Karvonen (heart rate reserve) method

A plain percentage of maximum heart rate ignores how fast your heart beats at rest. The Karvonen approach, named after the Finnish researcher who described it, uses your heart rate reserve, the gap between resting and maximum heart rate:

Target heart rate = resting heart rate + (maximum heart rate − resting heart rate) × intensity

Measure your resting pulse for one minute right after waking, lying down, before you get up or drink coffee, and average a few mornings. As fitness improves, resting heart rate tends to drop, so the Karvonen method reflects your conditioning in a way a simple percentage cannot. When you enter a resting heart rate above, the calculator switches to this method automatically and shows the plain-percentage figure for comparison.

Worked examples

Example 1: age 40, resting 60 bpm, 220 − age. Maximum heart rate is 180 and reserve is 180 − 60 = 120. Seventy percent intensity is 60 + 0.7 × 120 = 144 bpm, and 80 percent is 60 + 0.8 × 120 = 156 bpm. With a plain percentage the same 70 and 80 percent would be 126 and 144 bpm, so the Karvonen targets are 18 and 12 bpm higher. The lower your resting heart rate, the larger that gap becomes.

Example 2: age 60, no resting heart rate. The classic formula gives 160 and Tanaka gives 208 − 42 = 166. The fat burn zone (60 to 70 percent) is 96 to 112 bpm on the classic basis and roughly 100 to 116 bpm on the Tanaka basis. Six beats may look minor, but in practice it can be the difference between an easy aerobic effort and a moderate one, so use both the number and how you feel.

Example 3: age 30, resting 65 bpm, 220 − age. Maximum is 190 and reserve is 125. The fat burn zone is 65 + 0.6 × 125 = 140 up to 65 + 0.7 × 125 = 152.5, which rounds to 140 to 153 bpm. A plain percentage would give 114 to 133 bpm, which would set this person's easy-day target about 20 to 26 bpm too low.

Example 4: age 50, resting 55 bpm, Tanaka. Maximum is 208 − 35 = 173. The five zones by Karvonen are roughly 114 to 126, 126 to 138, 138 to 149, 149 to 161, and 161 to 173 bpm.

What each zone is used for

• Warm-up (50-60%): warm-ups, cool-downs, and recovery walks or jogs. You can talk without effort and your breathing barely changes. A sensible starting point for beginners and for the day after a hard session.
• Fat burn (60-70%): a base aerobic effort you can sustain for a long time while holding a conversation. A higher share of the energy comes from fat at this intensity, but that does not mean this is the only zone that helps with weight. Total energy in versus out over the day and week matters far more, and a harder zone burns more calories per minute.
• Cardio (70-80%): moderate to steady effort that builds cardiorespiratory endurance. You can speak in sentences but not hold a long chat. Common for tempo sessions and steady runs of 30 to 60 minutes.
• Anaerobic (80-90%): hard effort, a few words at a time. This is the "work" portion of interval training and can only be held briefly before recovery is needed.
• Max (90-100%): near-maximal effort lasting from seconds to a few minutes. Most recreational exercisers rarely need it, and people with cardiovascular risk should avoid it unless a clinician has cleared it.

A common beginner pattern is three sessions a week mostly in the first three zones, adding one interval session in the anaerobic zone only after about four weeks of adapting. For weekly activity targets, consult the physical activity guidelines from your national health authority or the World Health Organization.

When heart rate zones do not fit

• Medication. Drugs that slow the heart, such as beta blockers, lower both resting and exercise heart rate, so age-based formulas will overstate your limits. Ask your doctor for a target range.
• Heart rhythm problems, heart disease, pregnancy, or blood pressure medication. Follow the range your clinician gives you instead of a generic formula.
• Heat, dehydration, poor sleep, caffeine, illness, and stress can raise heart rate by 5 to 15 bpm at the same effort. A higher number on such a day is not automatically dangerous, but it is a cue to back off.
• Different sports. Running, cycling, and swimming recruit muscle differently, so maximum heart rate can differ by activity; swimming is often reported to produce lower values.
• Wrist sensors. Optical wrist sensors can lag or misread during intervals and arm-heavy movement. A chest strap is more dependable when accuracy matters.
• Warning symptoms. Chest pain, dizziness, unusual shortness of breath, or palpitations mean stop immediately, whatever the number on your watch says.

Judging effort without numbers

If you have no monitor, use the talk test: if you can sing, you are very easy; if you can hold a conversation, you are around the fat burn zone; if you can speak only in short sentences, you are in cardio to anaerobic territory; if you manage one or two words, you are working hard. A 10-point rate of perceived exertion scale is a useful companion. To take your pulse by hand, count beats at the wrist or neck for 15 seconds and multiply by four, and do it immediately after stopping, since heart rate falls quickly.

Common mistakes

• Treating a zone as an absolute rule. The range is a starting estimate. If your "easy zone" run leaves you unable to speak, the estimate may be too high for you; slow down.
• Skipping the warm-up. Begin about ten minutes in the lowest zone and build gradually instead of jumping straight to hard effort.
• Measuring resting heart rate at the wrong time. A reading taken after coffee or a workout inflates resting heart rate and, in turn, every Karvonen target. Use waking, lying-down values averaged over several days.
• Ignoring how you feel. On a hot or sleep-deprived day, hold the target heart rate and let the pace fall.
• Treating one test as final. Motivation and fatigue change a measured maximum. An estimated maximum is best read as a rough band.

Related tools

• Exercise Calorie Calculator for the energy cost of different activities
• Running Pace Calculator for planning an easy-zone pace
• BMR / TDEE Calculator for daily energy expenditure
• Sleep Cycle Calculator for planning the recovery that training depends on

This calculator gives general exercise-intensity references for healthy adults. It is not medical advice, diagnosis, or a prescription. If you have a health condition or any concerns, speak to a medical professional before you exercise.

Frequently Asked Questions