Determine Your Heart-Rate Zone

To estimate what your heart rate or pulse should be when you exercise, use this formula:

Subtract your age from 220. For example: If you are forty years old, then the answer is 180. This number is your estimated maximum heart rate in beats per minute.

Now, multiply that number (e.g., 180) by .65 and .85. The two numbers (117 and 153) tell you the range in which your heart rate should be during exercise.

You should spend the majority of your exercise time with your heart rate in the lower part of the range, reaching the higher part of the range only during brief interval sessions. If you’ve very fit, you can use a slightly different formula to determine the range of your heart rate during exercise. As a first step, subtract your age from 205, and then do the rest of the calculations described.