Fat Burning Zone Calculator

The fat burning zone is the exercise intensity range (typically 60-70% of maximum heart rate) at which fat provides the highest proportion of energy burned. At lower intensities, the body uses a greater percentage of fat for fuel, though total calories burned are lower than at higher intensities.

Not necessarily. While a greater percentage of energy comes from fat at lower intensities, higher intensity exercise burns more total calories per minute. Research shows that overall caloric deficit, not fat burning percentage, is the primary driver of fat loss. High-intensity intervals may burn more total fat overall in less time.

The most commonly used formula is 220 minus age (Fox et al.). The Tanaka formula (208 - 0.7 x Age) is somewhat more accurate for older adults and is used by the ACSM. For precision, a maximal exercise test is the gold standard but requires medical supervision for older or at-risk individuals.

Zone 1 (50-60%): Very light, active recovery. Zone 2 (60-70%): Light aerobic, fat burning zone. Zone 3 (70-80%): Aerobic fitness. Zone 4 (80-90%): Lactate threshold. Zone 5 (90-100%): Maximal effort, VO2 max. Most effective training programmes include all zones.

The Karvonen method uses heart rate reserve (HRR = Max HR - Resting HR) to personalise zones: Target HR = Resting HR + (Fraction x HRR). This is more accurate than simple percentage of max HR because it accounts for fitness level via resting heart rate. Resting heart rate should be measured at complete rest, ideally first thing in the morning.