Male
Female
Used for specific formulas like Gulati.
Enter the highest HR you have seen on a monitor during max effort.
Analysis Results
Traditional Formula (Fox, 220-Age):— bpm
Tanaka Formula (More Accurate):— bpm
Sex-Adjusted Formula (Gulati/Hunt):— bpm
Your Observed Max HR:— bpm
Training Zones (Based on Calculated Max)
Zone
Intensity
Range (bpm)
Benefit
function calculateHeartRate() {
// 1. Get Inputs
var ageInput = document.getElementById("hrAge");
var sexInput = document.getElementById("hrSex");
var observedInput = document.getElementById("observedMaxHR");
var age = parseFloat(ageInput.value);
var sex = sexInput.value;
var observed = parseFloat(observedInput.value);
// Validation
if (isNaN(age) || age 120) {
alert("Please enter a valid age.");
return;
}
// 2. Calculate Standard Formulas
// Fox: 220 – Age
var foxMax = 220 – age;
// Tanaka: 208 – (0.7 * Age)
var tanakaMax = 208 – (0.7 * age);
// Sex Adjusted (Gulati for women, Hunt for men/general)
// Gulati (Women): 206 – (0.88 * Age)
// For men, we will use a variation or standard Tanaka/Fox mix, but usually Hunt is 211 – 0.64*age
var adjustedMax = 0;
if (sex === "female") {
adjustedMax = 206 – (0.88 * age);
} else {
// Hunt formula for active men
adjustedMax = 211 – (0.64 * age);
}
// Rounding
foxMax = Math.round(foxMax);
tanakaMax = Math.round(tanakaMax);
adjustedMax = Math.round(adjustedMax);
// 3. Determine which HR to use for zones
// If observed is provided and valid, use it. Otherwise use Tanaka (generally accepted as better than Fox).
var targetMax = tanakaMax;
var isObservedSet = false;
if (!isNaN(observed) && observed > 0) {
targetMax = observed;
isObservedSet = true;
}
// 4. Update UI – Formulas
document.getElementById("resFox").innerHTML = foxMax + " bpm";
document.getElementById("resTanaka").innerHTML = tanakaMax + " bpm";
var adjustedLabel = (sex === "female") ? "Gulati Formula (Women):" : "Hunt Formula (Men):";
document.getElementById("resGulati").previousElementSibling.innerHTML = adjustedLabel;
document.getElementById("resGulati").innerHTML = adjustedMax + " bpm";
// 5. Comparison Logic
var comparisonBox = document.getElementById("comparisonBox");
var deviationText = document.getElementById("deviationText");
if (isObservedSet) {
comparisonBox.style.display = "block";
document.getElementById("resObserved").innerHTML = observed + " bpm";
// Calculate difference against the most common standard (Fox) and the Scientific standard (Tanaka)
var diff = observed – foxMax;
var diffTanaka = observed – tanakaMax;
var message = "";
if (diff > 0) {
message = "Result: Your observed max heart rate is " + diff + " bpm higher than the traditional '220 – Age' formula. ";
message += "This is very common. General formulas are population averages. Being higher than calculated does not necessarily indicate a health issue, but implies your training zones should be adjusted upwards.";
} else if (diff < 0) {
message = "Result: Your observed max heart rate is " + Math.abs(diff) + " bpm lower than the traditional formula.";
} else {
message = "Result: Your observed heart rate matches the traditional formula exactly.";
}
deviationText.innerHTML = message;
document.getElementById("zoneBasis").innerHTML = "Observed";
} else {
comparisonBox.style.display = "none";
document.getElementById("zoneBasis").innerHTML = "Calculated (Tanaka)";
}
// 6. Generate Zones
// Zone 1: 50-60%
// Zone 2: 60-70%
// Zone 3: 70-80%
// Zone 4: 80-90%
// Zone 5: 90-100%
var zones = [
{ z: "Zone 1", i: "Very Light", min: 0.50, max: 0.60, b: "Warm up, Recovery" },
{ z: "Zone 2", i: "Light", min: 0.60, max: 0.70, b: "Fat Burning, Endurance" },
{ z: "Zone 3", i: "Moderate", min: 0.70, max: 0.80, b: "Aerobic Capacity" },
{ z: "Zone 4", i: "Hard", min: 0.80, max: 0.90, b: "Anaerobic Threshold" },
{ z: "Zone 5", i: "Maximum", min: 0.90, max: 1.00, b: "Speed, Power" }
];
var tbody = document.getElementById("zoneTableBody");
tbody.innerHTML = ""; // Clear previous
for (var i = 0; i < zones.length; i++) {
var zone = zones[i];
var low = Math.round(targetMax * zone.min);
var high = Math.round(targetMax * zone.max);
var row = "
If you have ever used a heart rate monitor during an intense workout or a stress test, you might have noticed a number flashing on your screen that exceeds the standard "220 minus age" calculation. This is a very common scenario, yet it often causes confusion among athletes and fitness enthusiasts.
The discrepancy usually lies not with your heart, but with the formula itself. Understanding why your specific physiology differs from population averages is crucial for setting accurate training zones and avoiding undertraining.
The Limitation of Standard Formulas
The Fox formula (220 – Age) is the most widely cited equation in the fitness industry due to its simplicity. However, it was derived from a small dataset and was never intended to be a rigorous medical standard for individuals. Research suggests that this formula has a standard deviation of approximately 10–12 beats per minute (bpm).
This means that for a 30-year-old (Calculated Max: 190 bpm):
68% of the population will have a max HR between 178 and 202 bpm.
95% of the population will fall between 166 and 214 bpm.
If your max heart rate is 15 beats higher than the calculator predicts, you are likely just on the upper end of the bell curve, rather than a medical outlier.
Factors Influencing Max Heart Rate
Contrary to popular belief, maximum heart rate is not a direct indicator of fitness level. A sedentary person and an Olympic athlete of the same age might have the exact same maximum heart rate. However, several factors do play a role:
Genetics: This is the primary driver. Size of the heart and intrinsic firing rate of the sinoatrial node are genetically determined.
Age: Max HR declines with age, roughly by one beat per year, though this rate varies.
Altitude: High altitude can temporarily lower maximum heart rate capabilities due to reduced oxygen saturation.
Body Size: Smaller individuals (and often women) tend to have slightly higher heart rates than larger individuals.
Is a Higher Max Heart Rate Better?
Having a max heart rate higher than calculated is neither "good" nor "bad"—it is simply a physiological characteristic, similar to height. It does not mean you have a larger cardiovascular capacity; that is determined by your Stroke Volume and Cardiac Output.
However, knowing your true max is vital. If your true max is 200 bpm but you train based on a calculated max of 180 bpm, your training zones will be incorrect. You might be training in Zone 2 (recovery/endurance) when you intend to be in Zone 3 (aerobic), leading to suboptimal results.
Adjusting Your Training Zones
If you have confirmed your maximum heart rate is higher than the standard calculation through a field test or laboratory stress test, you should input that "Observed Max" into the calculator above. This will recalculate your Zone 1 through Zone 5 ranges.
For example, "Threshold Training" usually occurs at 80-90% of your max. If you underestimate your max by 20 beats, you will be training well below your lactate threshold, failing to elicit the desired physiological adaptation.
Note: Always consult a physician before performing a maximum effort physical test, especially if you have existing health conditions or are new to high-intensity exercise.