Leave blank to use the standard max heart rate formula. Enter RHR for the more accurate Karvonen formula.
Maximum Heart Rate (MHR):— BPM
Your Target Zones
Zone Intensity
Target Range (BPM)
Benefit
What Is the Formula to Calculate Your Target Heart Rate?
Calculating your target heart rate (THR) is essential for optimizing your fitness routine, ensuring you are working hard enough to see results but not so hard that you risk injury. The formula used depends on the level of accuracy required, with the two most common methods being the Standard Maximum Heart Rate method and the Karvonen Formula.
1. Standard Maximum Heart Rate Formula
The simplest way to estimate your target heart rate involves first calculating your Maximum Heart Rate (MHR). This provides a baseline estimation suitable for most beginners.
MHR = 220 – Age
Once you have your MHR, you calculate your target zones by multiplying the MHR by the desired intensity percentage (typically 50% to 85%).
Example: For a 40-year-old:
MHR = 220 – 40 = 180 BPM
Target Zone (50% intensity) = 180 × 0.50 = 90 BPM
2. The Karvonen Formula (Advanced Accuracy)
For a more personalized calculation, the Karvonen formula is preferred because it incorporates your Resting Heart Rate (RHR). This method accounts for your current fitness level, as fit individuals typically have lower resting heart rates.
Different heart rate zones achieve different physiological benefits:
Warm Up (50-60%): Good for beginners, warm-up, and cool-down.
Fat Burning (60-70%): Optimizes fat metabolism and basic endurance.
Aerobic (70-80%): Improves cardiovascular system and respiratory health.
Anaerobic (80-90%): Increases performance speed and lactic acid tolerance.
VO2 Max (90-100%): Maximum effort for short bursts to improve speed and power.
How to Measure Your Resting Heart Rate
To use the Karvonen formula effectively, measure your pulse before you get out of bed in the morning. Count the beats for 60 seconds. Do this for three mornings and take the average for the most accurate Resting Heart Rate input.
function calculateTargetHeartRate() {
// 1. Get Inputs
var ageInput = document.getElementById('thr_age');
var rhrInput = document.getElementById('thr_rhr');
var resultDiv = document.getElementById('thr-result');
var age = parseFloat(ageInput.value);
var rhr = parseFloat(rhrInput.value);
// 2. Validation
if (isNaN(age) || age 120) {
alert("Please enter a valid age between 1 and 120.");
return;
}
// 3. Calculate Max Heart Rate (Standard Formula)
var mhr = 220 – age;
document.getElementById('display_mhr').innerHTML = mhr + " BPM";
// 4. Define Zones (Percentages)
var zones = [
{ min: 0.50, max: 0.60, name: "Very Light (Warm Up)", benefit: "Recovery, Warm up" },
{ min: 0.60, max: 0.70, name: "Light (Fat Burn)", benefit: "Basic Endurance, Fat Burning" },
{ min: 0.70, max: 0.80, name: "Moderate (Aerobic)", benefit: "Cardiovascular Fitness" },
{ min: 0.80, max: 0.90, name: "Hard (Anaerobic)", benefit: "High Speed Endurance" },
{ min: 0.90, max: 1.00, name: "Maximum (VO2 Max)", benefit: "Max Performance, Speed" }
];
var tableHtml = "";
var useKarvonen = !isNaN(rhr) && rhr > 30 && rhr < mhr;
// 5. Generate Table Rows
for (var i = 0; i < zones.length; i++) {
var zone = zones[i];
var minBpm, maxBpm;
if (useKarvonen) {
// Karvonen Formula: ((MHR – RHR) * %) + RHR
var hrr = mhr – rhr;
minBpm = Math.round((hrr * zone.min) + rhr);
maxBpm = Math.round((hrr * zone.max) + rhr);
} else {
// Standard Formula: MHR * %
minBpm = Math.round(mhr * zone.min);
maxBpm = Math.round(mhr * zone.max);
}
tableHtml += "