Determine your Maximum Heart Rate (MHR) and specific training zones to optimize your running performance. Accurate heart rate zones help you train smarter, improve endurance, and prevent overtraining.
Male
Female
Tanaka (Recommended for Runners)
Fox Formula (Standard 220-Age)
Gulati (Women Specific)
Estimated Max Heart Rate0 BPM
Your Running Training Zones
Zone
Intensity
Heart Rate Range (BPM)
Training Benefit
Understanding Your Heart Rate Zones
Training by heart rate allows runners to target specific physiological adaptations. Most training plans follow the 80/20 rule: 80% of your running should be easy (Zones 1-2) and 20% hard (Zones 4-5).
Zone 1: Active Recovery (50-60% MHR)
Used for warm-ups, cool-downs, and recovery runs. Running in this zone aids in blood flow and muscle recovery without placing stress on the cardiovascular system. You should be able to hold a conversation effortlessly.
Zone 2: Aerobic Endurance (60-70% MHR)
This is the "bread and butter" zone for distance runners. It builds mitochondrial density and teaches your body to burn fat as fuel. Long runs are typically performed in this zone.
Zone 3: Tempo / Aerobic Power (70-80% MHR)
Often called "grey zone" training. It improves aerobic capacity and blood circulation in skeletal muscles. While useful, spending too much time here can lead to fatigue without the specific benefits of high-intensity intervals.
Zone 4: Lactate Threshold (80-90% MHR)
This implies running at a hard effort where your body produces lactate slightly faster than it can clear it. Training here raises your anaerobic threshold, allowing you to run faster for longer periods without "bonking."
Zone 5: VO2 Max (90-100% MHR)
Maximum effort used for short intervals and sprints. This zone improves the heart's stroke volume and your maximal oxygen uptake (VO2 Max). It is very taxing and should be done sparingly.
Formulas Used in This Calculator
While a laboratory stress test is the only 100% accurate way to determine MHR, several formulas provide close estimates for training purposes:
Fox Formula (220 – Age): The oldest standard, often criticized for inaccuracy in fit individuals or older adults.
Tanaka Formula (208 – 0.7 × Age): Generally considered more accurate for healthy adults and active runners across a wider age range.
Gulati Formula (206 – 0.88 × Age): A formula derived specifically for women, as the standard formulas often overestimate MHR in females.
function calculateRunningZones() {
// 1. Get Input Values
var ageInput = document.getElementById('runner_age').value;
var gender = document.getElementById('runner_gender').value;
var formula = document.getElementById('calc_formula').value;
// 2. Validate Input
var age = parseFloat(ageInput);
if (isNaN(age) || age 120) {
alert("Please enter a valid age between 10 and 120.");
return;
}
// 3. Calculate MHR based on selected formula
var mhr = 0;
if (formula === 'fox') {
mhr = 220 – age;
} else if (formula === 'gulati') {
// Gulati is specifically for women, if a man selects it, we revert to Tanaka or warn?
// For this logic, we will apply Gulati math regardless if selected,
// but usually, it is 206 – (0.88 * age).
mhr = 206 – (0.88 * age);
} else {
// Default to Tanaka
mhr = 208 – (0.7 * age);
}
// Round MHR
mhr = Math.round(mhr);
// 4. Calculate Zones
// Zone 1: 50-60%
var z1_min = Math.round(mhr * 0.50);
var z1_max = Math.round(mhr * 0.60);
// Zone 2: 60-70%
var z2_min = Math.round(mhr * 0.60);
var z2_max = Math.round(mhr * 0.70);
// Zone 3: 70-80%
var z3_min = Math.round(mhr * 0.70);
var z3_max = Math.round(mhr * 0.80);
// Zone 4: 80-90%
var z4_min = Math.round(mhr * 0.80);
var z4_max = Math.round(mhr * 0.90);
// Zone 5: 90-100%
var z5_min = Math.round(mhr * 0.90);
var z5_max = mhr;
// 5. Update UI
document.getElementById('display_mhr').innerHTML = mhr + " BPM";
document.getElementById('results-area').style.display = "block";
var tableHtml = `