A target heart rate calculator will explain to users how to measure their resting and non-resting heart beat. It will also help them understand hat their target heart rate should be relative to their age and fitness level.
For vigorous exercise, aim for a target heart rate of 70 to 85 percent of your maximum heart rate (MHR). Your MHR (roughly calculated as 220 minus your age) is the upper limit of what your cardiovascular system can handle during physical activity.
These numbers are estimates that provide an average value. Many people have a higher or lower MHR, sometimes by as much as 15 to 20 beats per minute. Disagreement exists on how to most accurately estimate your MHR and what percentage range to target.