Understanding your target heart rate zone is crucial for an effective weight loss program. During exercise, your heart rate increases to supply your muscles with oxygen. Maintaining your heart rate within a specific zone ensures you're burning a sufficient amount of calories and fat to support your weight loss goals. This calculator helps you determine your personalized target heart rate zones.
function calculateTargetHeartRate() {
var age = document.getElementById("age").value;
var weightKg = document.getElementById("weightKg").value;
var weightLossGoal = document.getElementById("weightLossGoal").value;
var exerciseFrequency = document.getElementById("exerciseFrequency").value;
var exerciseDuration = document.getElementById("exerciseDuration").value;
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Input validation
if (age <= 0 || weightKg <= 0 || weightLossGoal <= 0 || exerciseFrequency < 0 || exerciseDuration <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
// 1. Calculate Maximum Heart Rate (MHR) using the most common formula
var maxHeartRate = 220 – age;
// 2. Determine Weight Loss Target Heart Rate Zones
// General guideline for fat burning is 60-70% of MHR
// For weight loss, a slightly higher intensity might be beneficial, so we'll look at a broader range.
var fatBurningZoneLower = Math.round(maxHeartRate * 0.60);
var fatBurningZoneUpper = Math.round(maxHeartRate * 0.70);
var weightLossZoneLower = Math.round(maxHeartRate * 0.70); // Often overlaps with fat burning
var weightLossZoneUpper = Math.round(maxHeartRate * 0.85); // Includes more vigorous cardio for higher calorie burn
// 3. Estimate Calories Burned (This is a very rough estimate and depends on many factors)
// METs (Metabolic Equivalents) are used. A brisk walk or light jog might be around 5-7 METs.
// Calorie Burn = METs * body weight (kg) * duration (hours)
// We'll assume an average MET value for moderate-intensity exercise for weight loss.
var metValue = 6; // Assumed MET for moderate exercise
var exerciseDurationHours = exerciseDuration / 60;
var caloriesBurnedPerSession = metValue * parseFloat(weightKg) * exerciseDurationHours;
// 4. Estimate Time to Reach Weight Loss Goal (Very rough, assumes consistent calorie deficit)
// 1 kg of fat is approximately 7700 calories.
var totalCaloriesToBurn = parseFloat(weightLossGoal) * 7700;
var totalCaloriesBurnedPerWeek = caloriesBurnedPerSession * parseFloat(exerciseFrequency);
var weeksToReachGoal = totalCaloriesToBurn / totalCaloriesBurnedPerWeek;
// Display Results
var outputHTML = "