Enter for Karvonen Method (more accurate). Leave blank for Standard Method.
Maximum Heart Rate (MHR):— bpm
🔥 Fat Burning Zone (60-70%):— bpm
Target this range for optimal fat oxidation.
Aerobic Zone (70-80%):— bpm
Calculation Method Used:—
function calculateWeightLossZone() {
// Get input values
var ageInput = document.getElementById("hr_age");
var rhrInput = document.getElementById("hr_rhr");
// Get result elements
var resultsContainer = document.getElementById("hr_results");
var resMHR = document.getElementById("res_mhr");
var resZone = document.getElementById("res_zone");
var resAerobic = document.getElementById("res_aerobic");
var resMethod = document.getElementById("res_method");
// Parse values
var age = parseFloat(ageInput.value);
var rhr = parseFloat(rhrInput.value);
// Validate Age
if (isNaN(age) || age 120) {
alert("Please enter a valid age between 10 and 120.");
return;
}
// Calculate Maximum Heart Rate (Standard Formula)
var maxHeartRate = 220 – age;
var burnZoneLow, burnZoneHigh, aerobicZoneLow, aerobicZoneHigh;
var methodUsed = "";
// Determine Calculation Method
// If Resting Heart Rate is provided and valid, use Karvonen Formula
if (!isNaN(rhr) && rhr > 30 && rhr < maxHeartRate) {
// Karvonen Formula: Target Heart Rate = ((max HR − resting HR) × %Intensity) + resting HR
var heartRateReserve = maxHeartRate – rhr;
burnZoneLow = Math.round((heartRateReserve * 0.60) + rhr);
burnZoneHigh = Math.round((heartRateReserve * 0.70) + rhr);
aerobicZoneLow = Math.round((heartRateReserve * 0.70) + rhr);
aerobicZoneHigh = Math.round((heartRateReserve * 0.80) + rhr);
methodUsed = "Karvonen Formula (Based on Heart Rate Reserve)";
} else {
// Standard Formula: Percentage of Max Heart Rate
burnZoneLow = Math.round(maxHeartRate * 0.60);
burnZoneHigh = Math.round(maxHeartRate * 0.70);
aerobicZoneLow = Math.round(maxHeartRate * 0.70);
aerobicZoneHigh = Math.round(maxHeartRate * 0.80);
methodUsed = "Standard Formula (% of MHR)";
}
// Update UI
resMHR.innerHTML = maxHeartRate + " bpm";
resZone.innerHTML = burnZoneLow + " – " + burnZoneHigh + " bpm";
resAerobic.innerHTML = aerobicZoneLow + " – " + aerobicZoneHigh + " bpm";
resMethod.innerHTML = methodUsed;
// Show results
resultsContainer.style.display = "block";
}
Understanding Your Fat Burning Heart Rate Zone
When it comes to weight loss, not all exercise intensities are created equal. To maximize the amount of fat your body uses as fuel during a workout, experts recommend training in a specific heart rate range known as the "Fat Burning Zone" or "Weight Loss Zone." This calculator helps you identify your personal heart rate targets to optimize your cardio sessions.
What is the Weight Loss Zone?
The Weight Loss Zone is typically defined as 60% to 70% of your Maximum Heart Rate (MHR). While exercising at higher intensities (like HIIT) burns more total calories per minute, exercising in this lower-intensity zone encourages the body to source a higher percentage of its energy needs from fat stores rather than glycogen (carbohydrates).
Zone 1 (50-60%): Warm up and recovery. Very light intensity.
Zone 2 (60-70% – Weight Loss Zone): Comfortable conversation pace. The body oxidizes fat efficiently.
Zone 3 (70-80% – Aerobic): Improves cardiovascular endurance. You will sweat more and breathe heavier.
How the Calculation Works
This calculator employs two different methods depending on the data you provide:
1. The Standard Method (MHR)
If you only enter your age, we use the simple Maximum Heart Rate formula:
MHR = 220 – Age
Target Zone = MHR × 0.60 to MHR × 0.70
This provides a general baseline suitable for most beginners.
2. The Karvonen Formula (Recommended)
If you enter your Resting Heart Rate (RHR), we use the Karvonen formula. This is considered more accurate because it accounts for your individual fitness level (indicated by your resting heart rate).
To see results, consistency is key. Aim to keep your heart rate within the calculated range for at least 30 to 60 minutes per session. Activities like brisk walking, light jogging, cycling on flat terrain, or using an elliptical machine are excellent for maintaining this steady-state heart rate.
Note: Always consult with a healthcare provider before starting a new exercise regimen, especially if you have pre-existing health conditions.