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Heart Rate Zones

Health

Exercise Heart Rate Training Zones

Ranges of heart rate, expressed as a percentage of your maximum heart rate, used to guide exercise intensity for different training goals like fat burning, endurance, or peak performance.

Definition

Heart rate zones divide exercise intensity into bands based on what percentage of your maximum heart rate you're working at. Rather than guessing how hard you're pushing, checking your heart rate against these zones tells you objectively whether you're in an easy recovery effort or approaching your physical limit.

Different zones serve different training goals: lower zones build aerobic endurance and burn a higher proportion of fat, while higher zones improve speed, power, and cardiovascular capacity. Find your own zones with the Target Heart Rate Calculator, or check your current reading against them using the ECG Heart Rate Calculator.

Formula

Zones are calculated as a percentage range of estimated maximum heart rate:

Max HR ≈ 220 − age

Zone 1 (Very Light): 50-60% of Max HR Zone 2 (Light/Fat Burn): 60-70% of Max HR Zone 3 (Moderate/Aerobic): 70-80% of Max HR Zone 4 (Hard/Anaerobic): 80-90% of Max HR Zone 5 (Maximum): 90-100% of Max HR

Worked Example

A 40-year-old has an estimated Max HR of 220 − 40 = 180 bpm. Their Zone 2 fat-burning range would be 60-70% of 180, which works out to 108-126 bpm, a pace that should feel sustainable and conversational, not breathless.

Key Things to Know

  • The formula is an estimate, not a diagnosis. Athletes and people on certain medications, including beta-blockers, often see meaningfully different real-world numbers than the 220-minus-age formula predicts.
  • Zone 5 isn't meant to be sustained. It represents brief maximal efforts, like a sprint interval, not a pace you hold for an extended workout.
  • Resting heart rate matters too. A lower resting heart rate generally signals better cardiovascular fitness, and tracking it alongside your training zones over months gives a clearer fitness trend than any single workout.
  • Heart rate zones work alongside broader energy metrics like BMR and TDEE to give a fuller picture of how a workout fits into your overall calorie balance for the day.

Related Calculators

Target Heart Rate Calculator →Calculate your target heart rate zone for fat burning, cardio, and peak performance training, using the Karvonen formula and resting rate instantly.
ECG Heart Rate Calculator →Calculate heart rate from an ECG strip using the R-R interval, either by counting small or large boxes between beats or entering the interval in seconds.

Related Terms

BMRBasal Metabolic RateTDEETotal Daily Energy Expenditure

Frequently Asked Questions

Most training models use five zones, ranging from very light activity at 50-60% of max heart rate up to maximum effort at 90-100%. Some coaches simplify this to three zones (easy, moderate, hard), but the five-zone model is the most widely used in fitness apps and wearables.
Zone 2, roughly 60-70% of max heart rate, is often called the fat-burning zone because a higher percentage of calories burned there come from fat rather than carbohydrates. That said, higher-intensity zones burn more total calories per minute, so overall fat loss depends more on total energy expenditure than which zone you're technically in.
It's a rough population average, not a precise figure for any individual. Actual max heart rate varies by 10-20 beats per minute from the formula's estimate depending on genetics and fitness level, so a supervised max effort test gives a more accurate number if you need precision for serious training.
Zones 1 and 2 are the safest starting point for most beginners, building an aerobic base without excessive strain. Pushing into zones 4 and 5 too early, before building a fitness foundation, increases injury risk and can lead to burnout before real progress is made.
The percentage boundaries stay the same, but your resting heart rate typically drops as cardiovascular fitness improves, meaning you can sustain a higher workload at the same heart rate over time. This is one of the clearest signs of improving aerobic fitness on a wearable device.