Understanding your target heart rate zone is crucial for effective and safe exercise. It helps ensure you're working hard enough to gain cardiovascular benefits without overexerting yourself. This calculator will help you determine your estimated maximum heart rate and then calculate your target heart rate zones for moderate and vigorous intensity exercise.
Your Target Heart Rate Zones:
Estimated Maximum Heart Rate:— bpm
Moderate Intensity Zone (50-70% of Max HR):— bpm
Vigorous Intensity Zone (70-85% of Max HR):— bpm
function calculateTargetHeartRate() {
var ageInput = document.getElementById("age");
var maxHeartRateSpan = document.getElementById("maxHeartRate");
var moderateZoneSpan = document.getElementById("moderateZone");
var vigorousZoneSpan = document.getElementById("vigorousZone");
var age = parseFloat(ageInput.value);
if (isNaN(age) || age = 120) {
alert("Please enter a valid age between 1 and 120.");
maxHeartRateSpan.textContent = "– bpm";
moderateZoneSpan.textContent = "– bpm";
vigorousZoneSpan.textContent = "– bpm";
return;
}
// Karvonen Formula is often considered more accurate, but the simpler
// '220 – age' is widely used and understood for general guidance.
// We'll use the simpler one for this calculator.
var maxHeartRate = 220 – age;
var moderateLower = Math.round(maxHeartRate * 0.50);
var moderateUpper = Math.round(maxHeartRate * 0.70);
var vigorousLower = Math.round(maxHeartRate * 0.70);
var vigorousUpper = Math.round(maxHeartRate * 0.85);
maxHeartRateSpan.textContent = maxHeartRate + " bpm";
moderateZoneSpan.textContent = moderateLower + " – " + moderateUpper + " bpm";
vigorousZoneSpan.textContent = vigorousLower + " – " + vigorousUpper + " bpm";
}