Heart Rate for Burning Fat Calculator

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Fat Burning Heart Rate Calculator

Optimize your workout intensity for maximum fat loss

Measure while sitting still for 1 minute.

Your Target Fat Burning Zone:

0 – 0 BPM

Maximum Heart Rate: 0 BPM

Stay within this range during aerobic exercise to utilize fat as your primary fuel source.

Understanding Your Fat Burning Zone

The "Fat Burning Zone" is a specific range of heart rate intensity where your body burns a higher percentage of calories from stored fat rather than glycogen (carbohydrates). This typically occurs at 60% to 70% of your maximum heart rate.

The Science of the Calculation

This calculator uses the Karvonen Formula, which is widely considered more accurate than a simple percentage because it accounts for your Resting Heart Rate (RHR). The formula is:

  • Max Heart Rate (MHR) = 220 – Age
  • Heart Rate Reserve (HRR) = MHR – Resting Heart Rate
  • Target Zone = (HRR × % Intensity) + Resting Heart Rate

Example Calculation

If you are 40 years old with a resting heart rate of 60 BPM:

  1. Max Heart Rate: 220 – 40 = 180 BPM
  2. Heart Rate Reserve: 180 – 60 = 120 BPM
  3. 60% Intensity: (120 × 0.60) + 60 = 132 BPM
  4. 70% Intensity: (120 × 0.70) + 60 = 144 BPM
  5. Fat Burning Zone: 132 to 144 Beats Per Minute.

Tips for Best Results

To burn the most fat, aim for longer duration cardio (30-60 minutes) within this zone. While high-intensity interval training (HIIT) burns more total calories per minute, the lower-intensity fat-burning zone is ideal for recovery days or for those building an aerobic base without putting excessive stress on the central nervous system.

function calculateFatBurnZone() { var age = document.getElementById('ageInput').value; var rhr = document.getElementById('rhrInput').value; var resultDiv = document.getElementById('fatBurnResult'); // Validate inputs if (age === "" || age 110) { alert("Please enter a valid age."); return; } if (rhr === "" || rhr 200) { alert("Please enter a valid resting heart rate."); return; } var ageNum = parseFloat(age); var rhrNum = parseFloat(rhr); // Calculate Max Heart Rate var mhr = 220 – ageNum; // Calculate Heart Rate Reserve var hrr = mhr – rhrNum; if (hrr <= 0) { alert("Resting heart rate cannot be higher than maximum heart rate. Please check your inputs."); return; } // Karvonen Formula for Fat Burning Zone (60% to 70%) var lowBound = Math.round((hrr * 0.60) + rhrNum); var highBound = Math.round((hrr * 0.70) + rhrNum); // Update Display document.getElementById('lowBound').innerText = lowBound; document.getElementById('highBound').innerText = highBound; document.getElementById('maxHR').innerText = Math.round(mhr); // Show Result resultDiv.style.display = 'block'; // Smooth scroll to result if on mobile resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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