What is the difference between the Classic and Tanaka formulas?

The classic formula (220 − age) has been used for decades but tends to overestimate max HR for older adults and underestimate it for younger ones. The Tanaka formula (208 − 0.7 × age), derived from a 2001 meta-analysis of 351 studies, is generally more accurate across age groups.

What is the Karvonen method?

The Karvonen method uses Heart Rate Reserve (HRR = max HR − resting HR) to set zones, making them relative to your personal fitness level. A trained athlete with a low resting HR will have different zone boundaries than an untrained person of the same age.

Which zone is best for fat burning?

Zone 2 (aerobic, 60–70% max HR) burns the highest proportion of calories from fat, though total calorie burn is lower than at higher intensities. For overall fat loss, a mix of zones is most effective.

Heart Rate Zone Calculator

Understanding training zones

Heart rate zones divide exercise intensity into five bands, each eliciting different physiological adaptations. Training with awareness of your zones helps you structure workouts for specific goals: fat burning, aerobic base building, lactate threshold improvement, or anaerobic power.

Zone descriptions

Zone	% of max HR	Perceived effort	Primary benefit
Zone 1 - Recovery	50–60%	Very easy; can hold a conversation	Active recovery, warm-up, cool-down
Zone 2 - Aerobic base	60–70%	Easy; nose-breathing comfortable	Fat oxidation, endurance base, aerobic development
Zone 3 - Tempo	70–80%	Moderate; conversation possible but labored	Aerobic efficiency, cardiovascular fitness
Zone 4 - Threshold	80–90%	Hard; can speak only a few words	Lactate threshold, race pace endurance
Zone 5 - Anaerobic	90–100%	Maximum; cannot speak	Speed, power, VO₂ max

Max heart rate formula

The most common formula is 220 − age. This is a population average with a standard deviation of ±10–12 bpm - meaning your actual max HR could be 20+ bpm different. A more accurate formula (Tanaka, 2001): 208 − (0.7 × age). The only truly accurate way to find your max HR is a graded exercise test (GXT) supervised by a professional.

Training week structure

Research in endurance sports (particularly running and cycling) supports a 80/20 polarized training distribution for most recreational and competitive athletes:

~80% of sessions in Zone 1–2: builds aerobic base with minimal fatigue accumulation.
~20% of sessions in Zone 4–5: high-intensity work that drives fitness adaptations.
Minimize Zone 3: “junk miles” - hard enough to accumulate fatigue but not intense enough to drive the strongest adaptations.

Wearable accuracy

Consumer optical heart rate sensors (Apple Watch, Fitbit, Garmin) are approximately 95% accurate at rest but can show significant error during high-intensity exercise due to motion artifacts. Chest straps (Polar, Garmin HRM) use electrical signals and are considerably more reliable for Zone 4–5 training where precise HR monitoring matters most.

Heart rate reserve (Karvonen) method

The Karvonen formula uses heart rate reserve (HRR) - the difference between your max HR and resting HR - to define zones more personally:

Target HR = Resting HR + (HRR × Zone %)

For a fit individual with a low resting HR (e.g. 45 bpm), the Karvonen zones sit higher in absolute beats per minute than the simple percentage-of-max method, better reflecting their actual cardiovascular fitness level.

This calculator is for general information and is not medical advice. Consult a healthcare professional for personalized guidance.