Fox Formula (Standard: 220 – Age)
Tanaka (208 – 0.7 × Age)
Gulati (Women: 206 – 0.88 × Age)
Londeree-Moeschberger
If entered, we calculate zones using Heart Rate Reserve (Karvonen).
Estimated Maximum Heart Rate (MHR)
— BPM
Your Personal Training Zones
Zone
Intensity
Target Range (BPM)
Benefit
Understanding Your Heart Rate Zones
Target heart rate training involves using your heart rate (BPM) to monitor the intensity of your exercise. By training in specific "zones," you can optimize your workouts for fat burning, endurance, or peak performance.
The 5 Heart Rate Zones Explained
Zone 1: Very Light (50-60%)
This is the recovery zone. It helps with warm-ups, cool-downs, and active recovery. Training here improves overall health and helps muscles recover without placing stress on the body.
Zone 2: Light (60-70%)
Often called the "Fat Burning Zone." In this zone, the body becomes more efficient at oxidizing fat and transporting oxygen to muscles. It builds a solid aerobic base.
Zone 3: Moderate (70-80%)
The "Aerobic Zone." Training here improves cardiovascular endurance and blood circulation. It is the sweet spot for marathon training and general fitness improvement.
Zone 4: Hard (80-90%)
The "Anaerobic Zone." Here, you shift from aerobic to anaerobic metabolism. This zone increases your lactate threshold, allowing you to sustain high speeds for longer.
Zone 5: Maximum (90-100%)
The "Red Line" zone. This effort can only be sustained for very short bursts (sprinting). It develops fast-twitch muscle fibers and maximum speed.
Calculation Methodologies
There are several ways to estimate your Maximum Heart Rate (MHR). While a clinical stress test is the most accurate, formulas provide a good baseline:
Fox Formula (220 – Age): The most common standard, though it can oversimplify for very young or old individuals.
Tanaka (208 – 0.7 × Age): Generally considered more accurate for healthy adults over age 40.
Gulati (206 – 0.88 × Age): Specifically derived from research on women, providing a more accurate estimate for females.
Heart Rate Reserve (Karvonen Method)
If you enter your Resting Heart Rate, this calculator switches to the Karvonen formula. This method accounts for your fitness level by calculating zones based on the difference between your Max HR and Resting HR (Heart Rate Reserve), which is often more accurate for athletes.
function calculateHeartRateZones() {
// 1. Get Input Values
var ageInput = document.getElementById('hr_age');
var formulaSelect = document.getElementById('hr_formula');
var restingInput = document.getElementById('hr_resting');
var age = parseFloat(ageInput.value);
var formula = formulaSelect.value;
var restingHR = parseFloat(restingInput.value);
// 2. Validation
if (!age || isNaN(age) || age 120) {
alert("Please enter a valid age between 10 and 120.");
return;
}
// 3. Calculate Max Heart Rate (MHR)
var maxHR = 0;
var formulaName = "";
if (formula === 'fox') {
maxHR = 220 – age;
formulaName = "Formula: Fox (220 – Age)";
} else if (formula === 'tanaka') {
maxHR = 208 – (0.7 * age);
formulaName = "Formula: Tanaka (208 – 0.7 × Age)";
} else if (formula === 'gulati') {
maxHR = 206 – (0.88 * age);
formulaName = "Formula: Gulati (206 – 0.88 × Age)";
} else if (formula === 'londeree') {
maxHR = 206.3 – (0.711 * age);
formulaName = "Formula: Londeree-Moeschberger";
}
// Round MHR
maxHR = Math.round(maxHR);
// 4. Determine Calculation Mode (Standard vs Karvonen)
var useKarvonen = false;
if (!isNaN(restingHR) && restingHR > 30 && restingHR < maxHR) {
useKarvonen = true;
formulaName += " | Method: Karvonen (HRR)";
}
// 5. Display MHR
document.getElementById('hr_mhr_display').innerHTML = maxHR + " BPM";
document.getElementById('hr_formula_display').innerText = formulaName;
// 6. Define Zones Data
// Percentages: [Low, High]
var zones = [
{ name: "Zone 1", label: "Very Light", min: 0.50, max: 0.60, ben: "Recovery, Warm Up", css: "zone-row-1" },
{ name: "Zone 2", label: "Light", min: 0.60, max: 0.70, ben: "Fat Burning, Endurance", css: "zone-row-2" },
{ name: "Zone 3", label: "Moderate", min: 0.70, max: 0.80, ben: "Aerobic Fitness", css: "zone-row-3" },
{ name: "Zone 4", label: "Hard", min: 0.80, max: 0.90, ben: "Anaerobic Threshold", css: "zone-row-4" },
{ name: "Zone 5", label: "Maximum", min: 0.90, max: 1.00, ben: "Peak Performance", css: "zone-row-5" }
];
// 7. Generate Table HTML
var tableHTML = "";
for (var i = 0; i < zones.length; i++) {
var z = zones[i];
var lowerBPM, upperBPM;
if (useKarvonen) {
// Target HR = ((Max HR − Resting HR) × %Intensity) + Resting HR
var hrr = maxHR – restingHR;
lowerBPM = Math.round((hrr * z.min) + restingHR);
upperBPM = Math.round((hrr * z.max) + restingHR);
} else {
// Standard % of Max HR
lowerBPM = Math.round(maxHR * z.min);
upperBPM = Math.round(maxHR * z.max);
}
tableHTML += '