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Fat Burning Zone Calculator — What It Really Means

Calculate your five heart rate training zones from age using the Tanaka formula, with optional Karvonen (heart rate reserve) targets from your resting pulse.

If you enter your resting pulse, each zone also gets a Karvonen (heart rate reserve) range — usually more accurate for trained people.

Formula-based estimates for healthy adults — general fitness information, not medical advice. Consult a doctor before intense training.

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Reading age and resting heart rate
Estimating maximum heart rate
Building the five training zones

Result

This page opens the heart rate zone calculator with the low-intensity band highlighted — the range that gym equipment likes to label the fat burning zone.

Honest context: the fat burning zone is a marketing name for easy zone 2 exercise. At low intensity a higher percentage of the calories you burn comes from fat, which is true — but the total calories per minute are lower, so a harder session can burn more fat in absolute terms. No heart rate range melts fat by itself; the energy balance over days does.

That said, the zone is genuinely useful: it is sustainable for long sessions, easy to recover from and a solid default for beginners. Compute yours from age here, and add resting heart rate for the more personal Karvonen version.

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Accepted Formats & Rules

  • Five color-coded zones: recovery, easy, aerobic, threshold and maximum (50–100% of max HR).
  • Tanaka max HR as the primary estimate, classic 220 − age shown for reference.
  • Optional resting heart rate input adds Karvonen (HRR) ranges to every zone.
  • Copyable text summary of max HR and all five zones.

Key Benefits

✓ Two estimates, honestly labeled: the Tanaka formula (208 − 0.7 × age) as the primary number and the classic 220 − age alongside, with a clear note on the error both carry.
✓ Karvonen targets when you know your resting pulse: zones computed from heart rate reserve sit next to the plain %HRmax bands for direct comparison.
✓ Everything is calculated locally in your browser — age and resting heart rate are never sent anywhere.

Use Cases

  • • Find your zone 2 range for base-building runs and rides — the easy, conversational intensity endurance coaches prescribe most hours at.
  • • Set honest heart rate alerts on a sports watch using the Tanaka estimate instead of the folklore 220 − age rule.
  • • Enter your resting pulse to get Karvonen (heart rate reserve) targets — usually a better fit for trained athletes than plain %HRmax.