How to Calculate Fat Burning Zone Heart Rate

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Fat Burning Zone Calculator

Optimize your workout intensity for maximum fat loss

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Your Personal Results

Max Heart Rate

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Fat Burning Zone

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How to Calculate Your Fat Burning Zone

Calculating your fat burning zone is essential for tailoring your cardiovascular exercise to your specific fitness goals. This zone typically occurs at 60% to 70% of your maximum heart rate. At this intensity, your body utilizes a higher percentage of fat as fuel compared to carbohydrates.

The Karvonen Formula

This calculator uses the Karvonen Formula, which is widely considered more accurate than simple age-based formulas because it accounts for your Resting Heart Rate (RHR). By including your RHR, the calculation reflects your current level of cardiovascular fitness.

The Formula:
1. Max HR = 220 – Age
2. Heart Rate Reserve (HRR) = Max HR – Resting HR
3. Target HR = (HRR × %Intensity) + Resting HR

Real-World Example

Imagine a 40-year-old individual with a resting heart rate of 60 BPM:

  • Max HR: 220 – 40 = 180 BPM
  • Heart Rate Reserve: 180 – 60 = 120 BPM
  • Lower Limit (60%): (120 × 0.60) + 60 = 132 BPM
  • Upper Limit (70%): (120 × 0.70) + 60 = 144 BPM

In this example, the fat burning zone is between 132 and 144 beats per minute.

Why the Fat Burning Zone Matters

Training within this zone offers several benefits:

  • Efficiency: It maximizes the oxidation of fat stores.
  • Sustainability: You can typically maintain this intensity for longer durations (30-60 minutes).
  • Recovery: It places less stress on the central nervous system than high-intensity interval training (HIIT), allowing for more frequent workouts.
  • Endurance: It helps build a strong aerobic base, which improves overall heart health.
function calculateFatBurningZone() { var age = document.getElementById('age').value; var rhr = document.getElementById('restingHR').value; var resultsArea = document.getElementById('resultsArea'); var maxHRDisplay = document.getElementById('maxHRDisplay'); var zoneDisplay = document.getElementById('zoneDisplay'); var summaryText = document.getElementById('summaryText'); if (age === "" || rhr === "" || age <= 0 || rhr <= 0) { alert("Please enter valid positive numbers for both Age and Resting Heart Rate."); return; } age = parseFloat(age); rhr = parseFloat(rhr); // Calculate Max Heart Rate var mhr = 220 – age; // Calculate Heart Rate Reserve var hrr = mhr – rhr; if (hrr <= 0) { alert("Resting heart rate cannot be higher than maximum heart rate. Please check your inputs."); return; } // Karvonen Formula for Fat Burning (60% to 70% intensity) var lowerLimit = Math.round((hrr * 0.60) + rhr); var upperLimit = Math.round((hrr * 0.70) + rhr); // Update UI maxHRDisplay.innerText = mhr + " BPM"; zoneDisplay.innerText = lowerLimit + " – " + upperLimit + " BPM"; summaryText.innerText = "To stay in your fat burning zone, aim to keep your pulse between " + lowerLimit + " and " + upperLimit + " beats per minute during your steady-state cardio sessions."; resultsArea.style.display = "block"; resultsArea.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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