First, you need to measure your Maximum Heart Rate (MHR) by subtracting your age from 220. For example, if you are 25 years old, your MHR is 195.

The five heart rate zones are:

1. Easy/Fat Burning Zone: 50-65% of Maximum Heart Rate

2. Aerobic Zone: 66-76% of Maximum Heart Rate

3. Threshold Zone: 77-87% of Maximum Heart Rate

4. VO2 Max Zone: 88-93% of Maximum Heart Rate

5. Anaerobic Zone: 94-100% of Maximum Heart Rate

Once you have calculated your MHR, you can then calculate the heart rate range that you need to be in to be in a specific zone.

For example, if your MHR is 195, then you would need to have a heart rate between 97 and 183 beats per minute (bpm) to be in the Threshold zone.