Ideal Exercise Heart Rate Calculator

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Ideal Exercise Heart Rate Calculator

Optimize your workout intensity using the Karvonen Formula

Measured while sitting quietly.
70%

Your Results

Target Exercise Heart Rate: — Beats Per Minute

Your Estimated Max Heart Rate: — BPM

Intensity Zone BPM Range Benefit

How to Use the Ideal Exercise Heart Rate Calculator

Finding your "sweet spot" for cardiovascular exercise is crucial for both safety and effectiveness. This calculator uses the Karvonen Formula, which is widely considered more accurate than simple age-based formulas because it accounts for your individual resting heart rate (RHR).

The Science: The Karvonen Formula

While the standard formula (220 – age) provides a rough estimate of your maximum heart rate, the Karvonen method calculates your Heart Rate Reserve (HRR). HRR is the difference between your maximum heart rate and your resting heart rate. By applying your desired intensity percentage to your HRR and then adding back your resting heart rate, you get a target that is specifically calibrated to your current fitness level.

Formula: Target HR = ((Max HR − Resting HR) × % Intensity) + Resting HR

Heart Rate Training Zones Explained

  • Zone 1 (50-60%): Very Light. Ideal for warm-ups, cool-downs, and active recovery. Improves basic endurance and health.
  • Zone 2 (60-70%): Light (Fat Burn). This is the "aerobic base" zone. It's sustainable for long periods and primary uses fat as a fuel source.
  • Zone 3 (70-80%): Moderate (Aerobic). Improves cardiovascular efficiency and lung capacity. This is the classic "cardio" zone.
  • Zone 4 (80-90%): Hard (Anaerobic). Enhances speed, power, and metabolic rate. You can usually only maintain this for 10-20 minutes.
  • Zone 5 (90-100%): Maximum (Red Line). Sprinting or high-intensity intervals. Develops peak performance but can only be sustained for seconds or a few minutes.

Real-World Example

Let's look at a 40-year-old individual with a resting heart rate of 70 BPM who wants to train at 75% intensity (Zone 3):

  1. Max HR: 220 – 40 = 180 BPM
  2. Heart Rate Reserve: 180 – 70 = 110 BPM
  3. Target: (110 × 0.75) + 70 = 82.5 + 70 = 152.5 BPM

Without the Karvonen formula (using only 75% of 180), the target would be 135 BPM—a significant difference that could lead to undertraining.

Tips for Accuracy

To get the most accurate result, measure your resting heart rate in the morning right after you wake up, before getting out of bed. Take the average of three consecutive mornings. Always consult with a healthcare professional before starting a new high-intensity exercise program, especially if you have underlying health conditions.

function calculateHeartRate() { var age = parseFloat(document.getElementById('age').value); var rhr = parseFloat(document.getElementById('rhr').value); var intensityInput = parseFloat(document.getElementById('intensity').value); // Validation if (isNaN(age) || age 120) { alert("Please enter a valid age."); return; } if (isNaN(rhr) || rhr 120) { alert("Please enter a valid resting heart rate (typical range is 40-100)."); return; } var mhr = 220 – age; var hrr = mhr – rhr; // Calculate Target var targetIntensity = intensityInput / 100; var thr = Math.round((hrr * targetIntensity) + rhr); // Update UI document.getElementById('target-bpm').innerText = thr; document.getElementById('max-hr').innerText = mhr; document.getElementById('hr-results').style.display = 'block'; // Generate Zones Table var zones = [ { name: "Zone 1 (Recovery)", min: 0.50, max: 0.60, benefit: "Warm-up / Recovery" }, { name: "Zone 2 (Fat Burn)", min: 0.60, max: 0.70, benefit: "Endurance Building" }, { name: "Zone 3 (Aerobic)", min: 0.70, max: 0.80, benefit: "Cardio Fitness" }, { name: "Zone 4 (Anaerobic)", min: 0.80, max: 0.90, benefit: "Hardcore Training" }, { name: "Zone 5 (Max)", min: 0.90, max: 1.00, benefit: "Peak Performance" } ]; var tableBody = document.getElementById('zones-table'); tableBody.innerHTML = "; for (var i = 0; i = (zones[i].min * 100) && intensityInput <= (zones[i].max * 100)) { row.style.backgroundColor = "#fff9f9"; row.style.fontWeight = "bold"; } row.innerHTML = '' + zones[i].name + '' + '' + zoneMin + ' – ' + zoneMax + ' BPM' + '' + zones[i].benefit + ''; tableBody.appendChild(row); } // Scroll to results smoothly document.getElementById('hr-results').scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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