13 Heart Rate Reserve is Used to Calculate

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Heart Rate Reserve (HRR) & Target Heart Rate Calculator

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Your Calculation Results

Estimated Max Heart Rate (MHR): BPM
Heart Rate Reserve (HRR): BPM
Target Heart Rate: BPM

What is Heart Rate Reserve (HRR)?

Heart Rate Reserve (HRR) is the difference between your measured or predicted maximum heart rate and your resting heart rate. It represents the actual range of beats per minute available for your heart to utilize during exercise.

The Karvonen Formula

Heart Rate Reserve is primarily used to calculate your Target Heart Rate (THR) zones via the Karvonen Formula. This method is considered more accurate than simply taking a percentage of your Max Heart Rate because it accounts for your baseline fitness level (your resting heart rate).

Target Heart Rate = (HRR × % Intensity) + Resting Heart Rate

How to Use These Results

Depending on your fitness goals, you should target different intensity percentages based on your HRR:

  • Moderate Intensity (50% – 70%): Ideal for fat burning, warm-ups, and building basic cardiovascular endurance.
  • Vigorous Intensity (70% – 85%): Enhances aerobic capacity, improves respiratory health, and builds stamina.
  • High Intensity (85%+): Typically used for interval training (HIIT) and competitive performance training.

Example Calculation

If a 40-year-old individual has a resting heart rate of 60 BPM and wants to exercise at 75% intensity:

  1. Max HR: 220 – 40 = 180 BPM
  2. HRR: 180 – 60 = 120 BPM
  3. Target Heart Rate: (120 × 0.75) + 60 = 150 BPM
function calculateHRR() { var age = parseFloat(document.getElementById('age').value); var rhr = parseFloat(document.getElementById('rhr').value); var intensity = parseFloat(document.getElementById('intensity').value); var resultsDiv = document.getElementById('hrr-results'); if (isNaN(age) || isNaN(rhr) || age <= 0 || rhr <= 0) { alert('Please enter valid positive numbers for Age and Resting Heart Rate.'); return; } // Calculations var mhr = 220 – age; var hrr = mhr – rhr; if (hrr <= 0) { alert('Resting Heart Rate cannot be higher than or equal to Maximum Heart Rate. Please check your entries.'); return; } var thr = (hrr * (intensity / 100)) + rhr; // Display document.getElementById('mhr-val').innerText = Math.round(mhr); document.getElementById('hrr-val').innerText = Math.round(hrr); document.getElementById('thr-val').innerText = Math.round(thr); resultsDiv.style.display = 'block'; resultsDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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