Heart Rate Zone Calculator

Heart rate zones are ranges of beats per minute that correspond to different exercise intensities. There are five zones, each defined as a percentage of your maximum heart rate. Training in different zones produces different physiological adaptations — from active recovery and fat burning at the low end to peak speed and VO2 max development at the high end. Structuring your workouts across zones leads to more balanced and effective fitness gains.

Zone 2 (60–70% of max HR) is often called the fat burning zone because the body relies primarily on fat as its fuel source at this intensity. While higher intensities burn more total calories, a greater proportion comes from carbohydrates. For sustained fat loss, combining Zone 2 cardio sessions with overall caloric balance is most effective. Zone 2 also builds mitochondrial density and aerobic base without excessive recovery demands.

The standard formula is 220 minus your age. For a 30-year-old that gives a max HR of 190 bpm. This is an estimate with a margin of roughly ±10–12 bpm — genetics, fitness level, and medications can all shift your true maximum. If you have access to a lab stress test or have recorded a true all-out effort during a race or hard workout, enter that value in the "Advanced Options" section for more accurate zones.

Zone 2 training — also called low-intensity steady-state (LISS) cardio — has surged in popularity thanks to research on longevity and endurance performance. It involves sustained effort at 60–70% of max HR where you can hold a full conversation. Elite endurance athletes often spend 80% of their total training volume in Zone 2. Benefits include improved fat metabolism, mitochondrial efficiency, cardiac output, and faster recovery between hard sessions.

The Karvonen method uses your Heart Rate Reserve (HRR) — the difference between your maximum and resting heart rate — to calculate zones. The formula is: Target HR = Resting HR + (HRR × Zone percentage). Because it accounts for your cardiovascular fitness baseline, it produces more personalized and typically more accurate zones than the simple percentage method. A well-trained athlete with a low resting HR of 45 bpm will get meaningfully different zones than a sedentary person with a resting HR of 75 bpm, even at the same age.