Definition: The Karvonen Formula is a mathematical formula that helps you determine your target heart rate zone. The formula involves using your maximum heart rate (MHR) minus your age to come up with a target heart rate range (which is a percentage of your MHR). Staying within this range will help you work most effectively during your cardio workouts.
Below is an example of the Karvonen formula for a 23 year old person with a resting heart rate of 65 beats per minute (*to get your resting heart rate, take your pulse for one full minute when you first wake up in the morning or after you've resting for a while). This formula also includes an updated calculation of maximum heart rate (the previous formula was 220 - age, which has now been shown to be inaccurate):
206.9 - (0.67 x 23 (age)) = 191
191 - 65 (resting heart rate) = 126
126 * 65% (low end of heart rate zone) OR 85% (high end) = 82 OR 107
82 + 65 (resting heart rate) = 147
107 + 65 (rhr) = 172
The target heart rate zone for this person would be 147 to 172
Below is an example of the Karvonen formula for a 23 year old person with a resting heart rate of 65 beats per minute (*to get your resting heart rate, take your pulse for one full minute when you first wake up in the morning or after you've resting for a while). This formula also includes an updated calculation of maximum heart rate (the previous formula was 220 - age, which has now been shown to be inaccurate):
206.9 - (0.67 x 23 (age)) = 191
191 - 65 (resting heart rate) = 126
126 * 65% (low end of heart rate zone) OR 85% (high end) = 82 OR 107
82 + 65 (resting heart rate) = 147
107 + 65 (rhr) = 172
The target heart rate zone for this person would be 147 to 172
Sources:
Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol. 2001 Jan;37(1):153-6.

