We are no longer offering our Target Heart Rate Calculator because it has recently been proven an inaccurate measurement of the rate your heart should beat during aerobic exercise. Please read on for a more thorough explanation.
Most experts agree that a widely-used heart rate calculator formula—220 minus your age—may be inaccurate for many individuals. That target H.R. formula was derived from several different studies of men, some of whom were healthy, others of whom had coronary heart disease[i]. In 2010, researchers at Northwestern University found that a better formula for women ages 35 and older was 208 minus 88 % of age. A separate study found that the best way to estimate maximum heart rate in healthy, active people is to do a 200-meter sprint time trial, and then repeat it a few days later. Take the highest heart rate you achieve in those trials as your maximum heart rate.
If you want an exact number, experts recommend seeing an exercise physiologist for a treadmill test[ii]. This test typically involves running on a treadmill while hooked up to machines that monitor your heart rate and blood pressure, as well as how much oxygen you’re consuming. Every 3 minutes the treadmill gets faster and the incline gets steeper, until you reach the maximum effort you can sustain. Your heart rate at that maximum effort is your max heart rate. That said, even with an accurate max heart rate, there are still going to be limitations when you’re using a heart rate monitor to determine how hard you’re working.
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If a heart-rate monitor accidentally gets wet, say from rain or sweat, it might stop sensing your heart rate. Other machines might also interfere with the signals. Also, certain other variables that have little to do with your level of fitness are going to impact your heart rate. If you’re dehydrated, if it’s a superhot day, or if you’re in pain, your heart rate might skyrocket, even if you’re running at a slower pace.
