Heart Rate Zone Calculator App

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Heart Rate Zone Calculator

Optimize your training by calculating your specific intensity zones using the Karvonen Formula.

Your Personalized Heart Rate Zones

Based on a Max Heart Rate of BPM.

Zone Intensity Target Range (BPM)
Zone 1: Recovery 50% – 60%
Zone 2: Fat Burn 60% – 70%
Zone 3: Aerobic 70% – 80%
Zone 4: Anaerobic 80% – 90%
Zone 5: VO2 Max 90% – 100%

Understanding Heart Rate Zone Training

Using a heart rate zone calculator app is the most effective way to ensure you are training at the right intensity for your specific fitness goals. Whether you want to burn fat, increase your cardiovascular endurance, or improve your sprinting power, your heart rate provides a real-time window into how your body is responding to exercise.

The Karvonen Formula Explained

This calculator utilizes the Karvonen Formula, which is considered more accurate than simple percentage-based calculations because it accounts for your Resting Heart Rate (RHR). By including your RHR, the formula determines your Heart Rate Reserve (HRR), which reflects your actual heart rate range available for exercise.

Realistic Example:
If you are 35 years old with a resting heart rate of 65 BPM:
1. Max Heart Rate (MHR): 220 – 35 = 185 BPM
2. Heart Rate Reserve (HRR): 185 – 65 = 120 BPM
3. Zone 2 Lower Limit (60%): (120 * 0.60) + 65 = 137 BPM

Breakdown of the 5 Training Zones

Zone 1: Very Light (50-60%)

This zone is used primarily for active recovery after a hard workout or for warming up. It improves overall health and helps you recover faster from high-intensity efforts.

Zone 2: Light (60-70%)

Known as the "base" or "fat-burning" zone. In Zone 2, your body becomes more efficient at burning fat for fuel. This is the intensity where you should perform the majority of your aerobic base building.

Zone 3: Moderate (70-80%)

Training here improves your aerobic capacity and blood circulation. It is excellent for increasing the efficiency of your heart and skeletal muscles.

Zone 4: Hard (80-90%)

This is where you improve your speed endurance. Your body begins to produce lactic acid faster than it can clear it. Training in Zone 4 helps you sustain higher speeds for longer periods.

Zone 5: Maximum (90-100%)

Zone 5 is for short, high-intensity intervals. It improves your VO2 Max and anaerobic peak power. This zone is very demanding and should only be used sparingly by fit individuals.

How to Use This Heart Rate Zone Calculator

To get the most accurate results, you should measure your resting heart rate in the morning just after waking up, while still in bed. Enter your age and this resting pulse into the calculator above to get your custom zones. Use a wearable heart rate monitor during your workouts to track which zone you are currently in.

function calculateHRZones() { var age = document.getElementById("userAge").value; var rhr = document.getElementById("restingHR").value; if (!age || age <= 0 || !rhr || rhr <= 0) { alert("Please enter a valid age and resting heart rate."); return; } var mhr = 220 – age; var hrr = mhr – rhr; function getTarget(percent) { var bpm = (hrr * percent) + parseInt(rhr); return Math.round(bpm); } // Zone 1: 50-60% var z1Low = getTarget(0.50); var z1High = getTarget(0.60); // Zone 2: 60-70% var z2Low = getTarget(0.60); var z2High = getTarget(0.70); // Zone 3: 70-80% var z3Low = getTarget(0.70); var z3High = getTarget(0.80); // Zone 4: 80-90% var z4Low = getTarget(0.80); var z4High = getTarget(0.90); // Zone 5: 90-100% var z5Low = getTarget(0.90); var z5High = mhr; document.getElementById("displayMHR").innerText = mhr; document.getElementById("z1Range").innerText = z1Low + " – " + z1High + " BPM"; document.getElementById("z2Range").innerText = z2Low + " – " + z2High + " BPM"; document.getElementById("z3Range").innerText = z3Low + " – " + z3High + " BPM"; document.getElementById("z4Range").innerText = z4Low + " – " + z4High + " BPM"; document.getElementById("z5Range").innerText = z5Low + " – " + z5High + " BPM"; document.getElementById("hrResults").style.display = "block"; document.getElementById("hrResults").scrollIntoView({ behavior: 'smooth' }); }

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