Heart Rate Zone Calculator

What are heart rate zones?

Heart rate zones are ranges of heartbeats per minute that correspond to different exercise intensities. Each zone triggers specific physiological adaptations in your body. Training in different zones helps you target specific fitness goals, from burning fat and building aerobic endurance to increasing speed and VO2 max. Most fitness experts define five distinct zones based on percentages of your maximum heart rate.

Your maximum heart rate (max HR) is the highest number of beats per minute your heart can sustain during all-out effort. The simplest way to estimate it is the formula 220 minus your age. While lab testing (like a graded exercise test) provides the most accurate measurement, the age-based formula gives a useful starting point for most people.

The power of Zone 2 training

Zone 2 training (60-70% of max HR) has gained massive attention from endurance coaches, longevity researchers, and sports scientists. At this intensity, your body primarily burns fat for fuel while building mitochondrial density, the tiny powerhouses inside your muscle cells that produce energy. Over time, a strong Zone 2 base lets you exercise longer before fatigue sets in, improves cardiovascular health, and supports metabolic flexibility. Most elite endurance athletes spend 70-80% of their training time in Zone 2.

You can read more about the science and practical tips in our guide to Zone 2 training benefits.

How to train in each zone

Zone 1 (Recovery, 50-60%): Use this zone for warmups, cooldowns, and active recovery days. Walking, gentle cycling, and easy stretching all fall into this range. You should be able to hold a full conversation effortlessly.

Zone 2 (Aerobic, 60-70%): The foundation of endurance training. Long, steady runs, easy bike rides, and swimming at a comfortable pace. You can talk in sentences but not sing. This zone builds your aerobic base and maximizes fat oxidation.

Zone 3 (Tempo, 70-80%): A moderate effort where breathing becomes heavier. You can speak in short phrases. Tempo runs, group fitness classes, and steady-state cycling often land here. This zone improves aerobic efficiency and stamina.

Zone 4 (Threshold, 80-90%): Hard effort near your lactate threshold. You can only manage a few words at a time. Interval training, hill repeats, and race pace work happen here. This zone builds speed and anaerobic capacity.

Zone 5 (VO2 Max, 90-100%): Maximum effort that can only be sustained for short bursts. Speaking is nearly impossible. All-out sprints, short track intervals, and Tabata-style workouts target this zone. It increases VO2 max and peak power output. Learn more about VO2 max and how to test it with our VO2 max calculator.

Why resting heart rate matters for zones

The standard percentage-of-max method works as a rough guide, but it ignores your fitness level. Two people of the same age can have very different resting heart rates: a trained athlete might rest at 48 bpm while a sedentary person rests at 75 bpm. The Karvonen method accounts for this by using your heart rate reserve (max HR minus resting HR) to calculate zones. This produces more personalized, accurate training ranges.

If you do not know your resting heart rate, measure it first thing in the morning before getting out of bed, ideally over several days and take the average. Or use our resting heart rate guide and tips for accurate measurement. A lower resting heart rate generally indicates better cardiovascular fitness and faster recovery.

For deeper insight into how heart rate tracking improves your training, check out our article on heart rate monitoring.

Track your zones automatically with Cora

Cora tracks your real-time heart rate zones during every workout using your Apple Watch, Garmin, or Whoop. Instead of manually calculating zones, Cora uses your actual biometric data to set personalized thresholds that evolve as your fitness improves. You get live zone feedback during workouts, post-workout zone breakdowns, and weekly summaries of your training distribution across all five zones.

Download Cora free on the App Store and start training smarter with real-time heart rate zone tracking.