Target Heart Rate Calculator

What is heart rate

Heart rate is the number of times the heart beats per minute (bpm). Each beat pushes blood through the arteries, and that surge can be felt as a pulse at the wrist, on the side of the neck or anywhere a large artery runs close to the skin. To check it, place two fingers on the pulse, count the beats for 30 seconds and double the number, or use a fitness watch or chest strap.

Heart rate rises and falls constantly to match the body's demand for oxygen. Exercise, stress, excitement, heat, dehydration, caffeine, nicotine and many medications push it up; rest, sleep and some medications such as beta blockers slow it down. Because heart rate increases roughly in step with how hard the body is working, it is one of the most practical ways to gauge exercise intensity.

Maximum heart rate is the highest rate your heart can reach during an all-out effort. It declines with age and differs a good deal between people of the same age, by 10 to 12 bpm either way in many studies. The classic estimate is 220 minus age, attributed to Haskell and Fox. Later research found it tends to underestimate the maximum in older adults, leading to alternatives such as Tanaka's 208 minus 0.7 times age and the Nes formula of 211 minus 0.64 times age. The most accurate way to know your maximum is a supervised exercise test; people with heart conditions or other health concerns should talk to a doctor before attempting maximal efforts.

Resting heart rate

Resting heart rate is your pulse when you are calm and have been inactive for a while. It is best measured in the morning, before getting out of bed. For most adults it falls between 60 and 100 bpm. Regular aerobic exercise strengthens the heart so it pumps more blood with each beat, which lowers the resting rate; well-trained endurance athletes can rest in the 40s. A resting rate that is persistently above 100, or below 60 with symptoms such as dizziness or fainting, is worth discussing with a doctor.

Heart rate reserve

Heart rate reserve (HRR) is the difference between your maximum and resting heart rates, the range your heart can actually use during exercise. The Karvonen method sets targets as a percentage of this reserve added to the resting rate, which personalizes zones for people whose resting rate is unusually high or low.

For a 30-year-old with a resting rate of 70 bpm, the estimated maximum is 190 bpm and the reserve is 120 bpm. A target of 60% is 70 + 0.6 × 120 = 142 bpm.

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

max HR − resting HR

heart rate reserve (HRR)

intensity

fraction of reserve, e.g. 0.6 for 60%

Without a resting heart rate, the target is simply intensity × max HR.

Target heart rate zones

Training zones divide the range between easy and maximal effort into bands, each associated with a different kind of training effect. The American Heart Association describes moderate exercise as roughly 50% to 70% of maximum heart rate and vigorous exercise as about 70% to 85%.

Zone 1 (50–60%) is very light activity for warming up, cooling down and recovery. Zone 2 (60–70%) is comfortable, steady exercise that builds aerobic endurance and relies heavily on fat for fuel; it is sometimes called the fat-burning zone, though total calories burned are higher at harder efforts. Zone 3 (70–80%) is moderate-to-hard aerobic work that improves cardiovascular fitness. Zone 4 (80–90%) approaches the lactate threshold, where the body begins to rely more on anaerobic energy and fatigue builds quickly. Zone 5 (90–100%) is maximal effort that can be held only for short intervals and is used to develop speed and maximal oxygen uptake.

Most fitness plans spend the majority of time in zones 2 and 3, with a smaller share of harder intervals. People who are new to exercise, have health conditions or take medications that affect heart rate should start at the lower end and build up gradually.

Methods for measuring intensity

Heart rate is only one way to judge effort. Several other methods are widely used and can be combined.

The talk test is the simplest. During moderate activity you can talk but not sing. During vigorous activity you can say only a few words before pausing for breath. It needs no equipment and works well for people whose heart rate is affected by medication.

Ratings of perceived exertion (RPE) ask you to score how hard the effort feels, taking into account breathing, muscle fatigue and overall strain. The original Borg scale, developed by Swedish psychologist Gunnar Borg, runs from 6 (no exertion at all) to 20 (maximal exertion). The numbers were chosen so that, for a healthy young adult, the rating multiplied by ten roughly approximates heart rate: an RPE of 13, somewhat hard, corresponds to about 130 bpm. A rating of 12 to 14 is generally considered moderate intensity.

The modified Borg CR10 (category-ratio) scale runs from 0 to 10 and is easier for many people to use. It is common in clinical settings, for example in cardiac and pulmonary rehabilitation, and for rating breathlessness. A rating of 0 means nothing at all, 3 is moderate, 5 is hard, 7 is very hard and 10 is maximal.

Metabolic equivalents (METs) describe intensity in terms of energy use. Activities below 3 METs are light, 3 to 6 METs moderate and above 6 METs vigorous. Brisk walking is about 3.5 to 4 METs, and running at 6 miles per hour is around 10.

Laboratory measures are the most precise. A graded exercise test measures oxygen uptake (VO2) directly and can determine maximum heart rate, VO2 max and the lactate threshold, which athletes use to set very specific training zones. Fitness trackers estimate many of these values from heart rate data, but their estimates can be off for individuals.

Frequently asked questions

Sources

• American Heart Association – Target Heart Rates
• CDC – Measuring Physical Activity Intensity
• HHS – Physical Activity Guidelines for Americans