Fox Formula (Standard: 220 – Age)
Tanaka Formula (208 – 0.7 × Age)
Gulati Formula (Women: 206 – 0.88 × Age)
Haskell Formula (220 – Age, detailed)
Estimated Max Heart Rate (MHR):— bpm
Target Heart Rate Training Zones
Zone
Intensity
Range (bpm)
Benefit
*bpm = beats per minute
function calculateHeartRate() {
// 1. Get Input Values
var ageInput = document.getElementById("hrAge").value;
var formula = document.getElementById("hrFormula").value;
var resultBox = document.getElementById("calc-results");
var mhrDisplay = document.getElementById("resultMHR");
var tableBody = document.getElementById("zoneTableBody");
// 2. Validate Input
if (!ageInput || isNaN(ageInput) || ageInput 120) {
alert("Please enter a valid age between 1 and 120.");
return;
}
var age = parseFloat(ageInput);
var mhr = 0;
// 3. Calculate Maximum Heart Rate (MHR) based on Formula
if (formula === "fox") {
mhr = 220 – age;
} else if (formula === "tanaka") {
mhr = 208 – (0.7 * age);
} else if (formula === "gulati") {
mhr = 206 – (0.88 * age);
} else if (formula === "haskell") {
// Often synonymous with Fox in general usage, but strict Haskell & Fox is 220-age.
// We will treat it same as Fox for general purposes or allow for slight variations if needed.
mhr = 220 – age;
}
mhr = Math.round(mhr);
// 4. Update Result Display
mhrDisplay.innerHTML = mhr + " bpm";
resultBox.style.display = "block";
// 5. Calculate Zones
// Zone 1: Very Light (50-60%)
// Zone 2: Light (60-70%)
// Zone 3: Moderate (70-80%)
// Zone 4: Hard (80-90%)
// Zone 5: Maximum (90-100%)
var zones = [
{
name: "Zone 1",
intensity: "50% – 60%",
min: Math.round(mhr * 0.50),
max: Math.round(mhr * 0.60),
benefit: "Warm Up / Recovery",
class: "zone-1"
},
{
name: "Zone 2",
intensity: "60% – 70%",
min: Math.round(mhr * 0.60),
max: Math.round(mhr * 0.70),
benefit: "Fat Burning / Endurance",
class: "zone-2"
},
{
name: "Zone 3",
intensity: "70% – 80%",
min: Math.round(mhr * 0.70),
max: Math.round(mhr * 0.80),
benefit: "Aerobic Fitness",
class: "zone-3"
},
{
name: "Zone 4",
intensity: "80% – 90%",
min: Math.round(mhr * 0.80),
max: Math.round(mhr * 0.90),
benefit: "Anaerobic Capacity",
class: "zone-4"
},
{
name: "Zone 5",
intensity: "90% – 100%",
min: Math.round(mhr * 0.90),
max: mhr,
benefit: "Maximum Effort / Speed",
class: "zone-5"
}
];
// 6. Populate Table
var tableHTML = "";
for (var i = 0; i < zones.length; i++) {
tableHTML += "
";
tableHTML += "
" + zones[i].name + "
";
tableHTML += "
" + zones[i].intensity + "
";
tableHTML += "
" + zones[i].min + " – " + zones[i].max + " bpm
";
tableHTML += "
" + zones[i].benefit + "
";
tableHTML += "
";
}
tableBody.innerHTML = tableHTML;
}
How to Calculate Age Predicted Heart Rate
Understanding your Maximum Heart Rate (MHR) is the foundation of effective cardiovascular training. By determining your age-predicted heart rate, you can define specific training zones that target fat loss, aerobic endurance, or anaerobic performance. While a clinical stress test is the gold standard for measurement, mathematical formulas provide a convenient and generally accurate estimate for most individuals.
Why it matters: Training at the wrong intensity can lead to lackluster results or overtraining injuries. Knowing your numbers helps you train smarter, not just harder.
Common Formulas for Heart Rate Calculation
Several formulas exist to estimate your MHR. The calculator above allows you to toggle between the most scientifically recognized methods:
1. The Fox Formula (Standard)
This is the most widely known formula used in general fitness circles. It is simple to calculate but has a higher margin of error for older adults.
Formula:220 - Age = MHR
2. The Tanaka Formula
Published in 2001, this formula is often considered more accurate for healthy adults across a wider age range compared to the Fox formula.
Formula:208 - (0.7 × Age) = MHR
3. The Gulati Formula (For Women)
Research published in Circulation suggests that the standard calculation often overestimates MHR for women. The Gulati formula is specifically calibrated for female physiology.
Formula:206 - (0.88 × Age) = MHR
Understanding Target Heart Rate Zones
Once you have your Maximum Heart Rate, you can break it down into five distinct training zones. Each zone serves a different physiological purpose:
Zone 1 (50-60% MHR): Used for warm-ups, cool-downs, and active recovery. It aids in blood flow and muscle recovery.
Zone 2 (60-70% MHR): The "Fat Burning" zone. The body relies heavily on fat oxidation for fuel. It is sustainable for long durations.
Zone 3 (70-80% MHR): The aerobic zone. Training here improves lung capacity and strengthens the heart.
Zone 4 (80-90% MHR): The anaerobic threshold. Exercises in this zone produce lactic acid and improve high-intensity performance.
Zone 5 (90-100% MHR): Peak effort. Sustainable only for very short bursts (sprints or intervals).
Factors Affecting Heart Rate
While age is the primary variable in these calculations, remember that these are estimates. Several factors can influence your actual maximum heart rate:
Fitness Level: Elite athletes may have slightly lower maximum heart rates but significantly lower resting heart rates.
Medications: Beta-blockers and other medications can artificially lower your maximum heart rate.
Temperature & Altitude: High heat, humidity, or altitude can elevate your heart rate during exercise.
Stress & Caffeine: Both physiological and psychological stimulants can raise your baseline and exercising heart rate.
How to Use This Data
To use these numbers effectively, consider wearing a heart rate monitor or smartwatch during exercise. Aim to keep your heart rate within the specific "bpm" range provided by the calculator for the duration of your workout block. For example, if your goal is weight management, try to maintain a steady pace in Zone 2 for 45 minutes. If you are training for a 5K race, incorporate intervals that push into Zone 4.
Disclaimer: This calculator is for informational purposes only. Always consult a physician before beginning a new exercise program, especially if you have a history of heart conditions.