How to find your target heart rate

Calculate your target heart-rate zone by subtracting your age from 220 to get your maximum heart rate, and then multiplying that number by 0.7 (for the lower end of your target range) and 0.85 (for the upper end). For a 55-year-old, for example, the maximum heart rate would be 165 beats per minute, and the range during exercise is 116 and 140 beats per minute. Those numbers are approximate; individual targets might vary.