Male
Female
Required for high-precision formulas (Gulati).
Tanaka (Recommended for Adults)
Fox (Standard 220-Age)
Gulati (Specific for Women)
Estimated Maximum Heart Rate0 BPM
Target Heart Rate Zones:
Zone
Intensity
Range (BPM)
*Always consult a physician before starting a vigorous exercise program.
function calculateHeartRate() {
// 1. Get input values by ID
var ageInput = document.getElementById("mhr-age");
var genderSelect = document.getElementById("mhr-gender");
var formulaSelect = document.getElementById("mhr-formula");
var resultContainer = document.getElementById("mhr-result-container");
var bpmDisplay = document.getElementById("mhr-final-bpm");
var zoneBody = document.getElementById("mhr-zone-body");
// 2. Parse values
var age = parseFloat(ageInput.value);
var gender = genderSelect.value;
var formula = formulaSelect.value;
// 3. Validation
if (isNaN(age) || age 120) {
alert("Please enter a valid age between 1 and 120.");
return;
}
// 4. Calculate MHR based on selected formula
var maxHeartRate = 0;
// Formula Logic
if (formula === "fox") {
// Fox Formula: 220 – Age
maxHeartRate = 220 – age;
} else if (formula === "gulati") {
// Gulati Formula (Best for women): 206 – (0.88 * Age)
// If male is selected but gulati chosen, warn or default to Tanaka?
// We will stick to the math: Gulati was derived specifically for women.
// If user forces Gulati as Male, we apply the math regardless, but usually, it's for females.
// However, strictly adhering to logic:
maxHeartRate = 206 – (0.88 * age);
} else {
// Tanaka Formula (Default/Recommended): 208 – (0.7 * Age)
maxHeartRate = 208 – (0.7 * age);
}
// Auto-correct for Gulati/Gender mismatch suggestion logic (Internal check, but we just run the math)
// If user selects Female and Tanaka, it's fine. If Female and Fox, fine.
var mhrRounded = Math.round(maxHeartRate);
// 5. Calculate Zones
// Zone 1: 50-60% (Warm up)
// Zone 2: 60-70% (Fat Burn)
// Zone 3: 70-80% (Aerobic)
// Zone 4: 80-90% (Anaerobic)
// Zone 5: 90-100% (VO2 Max)
var z1_min = Math.round(maxHeartRate * 0.50);
var z1_max = Math.round(maxHeartRate * 0.60);
var z2_min = Math.round(maxHeartRate * 0.60);
var z2_max = Math.round(maxHeartRate * 0.70);
var z3_min = Math.round(maxHeartRate * 0.70);
var z3_max = Math.round(maxHeartRate * 0.80);
var z4_min = Math.round(maxHeartRate * 0.80);
var z4_max = Math.round(maxHeartRate * 0.90);
var z5_min = Math.round(maxHeartRate * 0.90);
var z5_max = mhrRounded;
// 6. Generate Table HTML
var tableHtml = "";
tableHtml += '
Determining your Maximum Heart Rate (MHR) is a fundamental step in designing an effective cardiovascular training program. Your MHR represents the highest number of beats per minute (BPM) your heart can achieve during maximum physical exertion. Knowing this number allows you to calculate specific target heart rate zones for fat loss, aerobic conditioning, and athletic performance.
1. The "Fox" Formula (The Standard)
For decades, the most widely referenced calculation has been the Fox formula. It is the simplest to remember and is often found on cardio equipment in gyms.
MHR = 220 – Age
Example: For a 40-year-old individual, the calculation is 220 – 40 = 180 BPM.
Critique: While easy to use, research has shown this formula can underestimate MHR in older adults and overestimate it in younger individuals. It has a standard deviation of roughly 10-12 beats per minute.
2. The Tanaka Formula (The Modern Standard)
Published in 2001, the Tanaka equation is considered more accurate for healthy adults of varying ages. It smoothens the curve of heart rate decline as we age.
MHR = 208 – (0.7 × Age)
Example: For a 40-year-old: 0.7 × 40 = 28. Then, 208 – 28 = 180 BPM. Example: For a 60-year-old: 0.7 × 60 = 42. Then, 208 – 42 = 166 BPM (Compared to 160 BPM using the Fox formula).
3. The Gulati Formula (Specific for Women)
Research led by Dr. Martha Gulati suggested that the traditional calculation (220 – Age) frequently overestimates maximum heart rate in women. This formula provides a more gender-specific baseline.
MHR = 206 – (0.88 × Age)
Example: A 40-year-old woman would calculate: 0.88 × 40 = 35.2. Then, 206 – 35.2 = 171 BPM (rounded).
Understanding Target Heart Rate Zones
Once you have calculated your MHR using the tool above, you can determine your training intensity zones:
Zone 1 (50-60%): Warm-up and recovery. Improves overall health and helps recovery after hard workouts.
Zone 2 (60-70%): Fat Burning. The body relies more on fat as a fuel source at this lower intensity.
Zone 3 (70-80%): Aerobic Capacity. Improves blood circulation and skeletal muscle efficiency.
Zone 4 (80-90%): Anaerobic Threshold. Increases speed and lactate tolerance.
Zone 5 (90-100%): Maximum Effort. Sustainable only for very short bursts (sprinting).
Safety Considerations
Calculations provide an estimate based on population averages. Individual genetics, medication (such as beta-blockers), and fitness levels can cause significant variances. The only way to determine your true absolute maximum heart rate is through a graded stress test monitored by a physician or cardiologist.