Heart rate zones can be used to train more effectively. Working within each zone has a specific training effect and knowing your zones will help you train more effectively.
There are two ways to calculate your heart rate training zones.
Maximum Heart Rate
Heart Rate Reserve
The second method uses your heart rate reserve to determine the zones.
Heart rate reserve, sometimes known as working heart rate, is simply your maximum heart rate minus your resting heart rate. See our article on training by heart rate for details of how to calculate your resting and maximum heart rates.
The heart rate reserve method is likely to provide slightly more accurate results.