Zone 2 Heart Rate Calculator
For better accuracy using the Karvonen method. Measure this upon waking up.
Your Zone 2 Training Range:
How to Calculate Zone 2 Cardio Heart Rate
Zone 2 training is often called "the base building zone." It is the intensity level where your body primarily uses fat as its main fuel source and develops mitochondrial efficiency. This calculator uses the Karvonen Formula, which incorporates your Resting Heart Rate (RHR) for a more personalized and accurate result than the standard "220 minus age" formula.
The Science Behind Zone 2
In Zone 2, your body stays below the first ventilatory threshold (VT1). At this intensity, you should be able to maintain a full conversation without gasping for air—often called the "Talk Test." This intensity is usually between 60% and 70% of your Heart Rate Reserve (HRR).
How the Calculation Works
Our calculator follows these specific mathematical steps:
- Max Heart Rate (MHR): Calculated as 220 – Age.
- Heart Rate Reserve (HRR): Calculated as MHR – Resting Heart Rate.
- Lower Bound (60%): (HRR × 0.60) + Resting Heart Rate.
- Upper Bound (70%): (HRR × 0.70) + Resting Heart Rate.
Example Calculation
If you are 40 years old with a resting heart rate of 60 BPM:
- Max HR: 220 – 40 = 180 BPM
- HRR: 180 – 60 = 120 BPM
- Low End (60%): (120 * 0.6) + 60 = 132 BPM
- High End (70%): (120 * 0.7) + 60 = 144 BPM
- Zone 2 Target: 132 – 144 BPM
Tips for Zone 2 Success
Most beginners make the mistake of going too fast. If you feel a "burn" in your muscles or find yourself breathing through your mouth heavily, you have likely entered Zone 3. Focus on consistency and duration; Zone 2 sessions should typically last 45 to 90 minutes for maximum aerobic benefit.