Best for fat burning and basic cardiovascular health.
Vigorous Intensity (70% – 85%)
Best for improving aerobic capacity and athletic performance.
How Do You Calculate Target Heart Rate Range?
Calculating your target heart rate (THR) is essential for maximizing the efficiency of your workouts while ensuring you stay within a safe cardiovascular limit. The most accurate way to find your range is through the Karvonen Formula, which takes your resting heart rate into account.
The calculation follows three primary steps:
Find Maximum Heart Rate (MHR): Subtract your age from 220. (Example: For a 40-year-old, 220 – 40 = 180 bpm).
Determine Heart Rate Reserve (HRR): Subtract your resting heart rate from your MHR.
Apply Intensity Percentages: Multiply your HRR by the intensity (e.g., 0.50 for 50%) and add back your resting heart rate.
The Science of Training Zones
Exercise scientists generally categorize physical activity into different intensity levels based on how close you are to your maximum capacity:
Zone
Intensity %
Benefit
Light
50% – 60%
Warm-up, recovery, and weight maintenance.
Moderate
60% – 70%
Building endurance and metabolism efficiency.
Aerobic
70% – 80%
Improving cardiovascular strength and lung capacity.
Anaerobic
80% – 90%
Increasing speed and power (High-Intensity Interval Training).
Example Calculation (Real-World Numbers)
Suppose you are 30 years old with a resting heart rate of 60 bpm. Here is how you calculate the lower end of the vigorous zone (70%):
MHR: 220 – 30 = 190 bpm
HRR: 190 – 60 = 130 bpm
70% Target: (130 x 0.70) + 60 = 151 bpm
Using this math, your heart rate should reach approximately 151 beats per minute to be in the vigorous aerobic zone.
Why Monitoring Matters
If your heart rate is too low, you may not be challenging your heart enough to see physiological changes. Conversely, if it is consistently too high, you risk overtraining, injury, or cardiovascular strain. Using a heart rate monitor or smartwatch during exercise allows you to stay within these calculated bounds for optimal results.
function calculateTHR() {
var age = document.getElementById("userAge").value;
var rhr = document.getElementById("restingHR").value;
var resultDiv = document.getElementById("thrResult");
// Validation
if (age === "" || rhr === "" || age <= 0 || rhr <= 0) {
alert("Please enter valid positive numbers for both Age and Resting Heart Rate.");
return;
}
var ageNum = parseFloat(age);
var rhrNum = parseFloat(rhr);
// Calculations using Karvonen Formula
// 1. Max Heart Rate
var mhr = 220 – ageNum;
// 2. Heart Rate Reserve
var hrr = mhr – rhrNum;
if (hrr <= 0) {
alert("Resting heart rate cannot be higher than maximum heart rate. Please check your inputs.");
return;
}
// 3. Moderate Intensity (50% to 70%)
var modLow = Math.round((hrr * 0.50) + rhrNum);
var modHigh = Math.round((hrr * 0.70) + rhrNum);
// 4. Vigorous Intensity (70% to 85%)
var vigLow = Math.round((hrr * 0.70) + rhrNum);
var vigHigh = Math.round((hrr * 0.85) + rhrNum);
// Display results
document.getElementById("mhrText").innerHTML = "Based on your age, your estimated Maximum Heart Rate is " + mhr + " BPM.";
document.getElementById("moderateRange").innerText = modLow + " – " + modHigh + " BPM";
document.getElementById("vigorousRange").innerText = vigLow + " – " + vigHigh + " BPM";
resultDiv.style.display = "block";
resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}