Zone 2 Heart Rate Calculator

Zone 2 heart rate is the intensity range where your body primarily uses fat as fuel, builds aerobic endurance, and improves metabolic efficiency. It corresponds to 60-70% of your maximum heart rate (or 60-70% of heart rate reserve using the Karvonen method). This zone is often called the "aerobic base" or "endurance" zone and is the foundation of effective endurance training.

The 80/20 rule, used by elite endurance coaches, recommends spending 80% of your weekly training volume in Zones 1-2 and only 20% in Zones 4-5. Most recreational athletes make the mistake of spending too much time in Zone 3 (the "dead zone"), which is too hard for aerobic development but too easy for threshold gains.

There are two common methods. Both start with your maximum heart rate (MHR).

Method 1: % of Max HR (simple)
Zone 2 = MHR × 0.60 to MHR × 0.70
Example: MHR 187 → Zone 2 is 112-131 bpm

Method 2: Karvonen (heart rate reserve)
Zone 2 = RHR + (HRR × 0.60) to RHR + (HRR × 0.70)
Where HRR = MHR − RHR
Example: MHR 187, RHR 70 → HRR = 117 → Zone 2 is 140-152 bpm

The Karvonen method is more accurate because it accounts for your resting heart rate, which reflects your current fitness level. Use our calculator to see both methods side by side.