Please enter valid numbers for Age and Resting Heart Rate.
Estimated Max Heart Rate
— bpm
Minimum Training Heart Rate (50%)
— bpm
Heart Rate Reserve (HRR)
— bpm
Training Zones (Karvonen Formula)
Zone
Intensity
Heart Rate Range (BPM)
Benefit
function calculateHeartRate() {
// Get inputs
var ageInput = document.getElementById('age').value;
var rhrInput = document.getElementById('resting_hr').value;
var errorMsg = document.getElementById('error-msg');
var resultsArea = document.getElementById('results-area');
// Parse values
var age = parseFloat(ageInput);
var rhr = parseFloat(rhrInput);
// Validation
if (isNaN(age) || isNaN(rhr) || age <= 0 || rhr <= 0) {
errorMsg.style.display = 'block';
resultsArea.style.display = 'none';
return;
} else {
errorMsg.style.display = 'none';
resultsArea.style.display = 'block';
}
// Calculations
// 1. Max Heart Rate (MHR) = 220 – Age (Standard Formula)
var mhr = 220 – age;
// 2. Heart Rate Reserve (HRR) = MHR – Resting HR
var hrr = mhr – rhr;
// Karvonen Formula: Target HR = (HRR * %Intensity) + Resting HR
// Calculate Zone Boundaries
var z1Min = Math.round((hrr * 0.50) + rhr);
var z1Max = Math.round((hrr * 0.60) + rhr);
var z2Min = Math.round((hrr * 0.60) + rhr); // Usually z1Max + 1, but for simplicity of ranges we align
var z2Max = Math.round((hrr * 0.70) + rhr);
var z3Min = Math.round((hrr * 0.70) + rhr);
var z3Max = Math.round((hrr * 0.80) + rhr);
var z4Min = Math.round((hrr * 0.80) + rhr);
var z4Max = Math.round((hrr * 0.90) + rhr);
var z5Min = Math.round((hrr * 0.90) + rhr);
var z5Max = mhr;
// Update Result Cards
document.getElementById('max-hr-display').innerHTML = mhr + " bpm";
document.getElementById('min-train-hr-display').innerHTML = z1Min + " bpm";
document.getElementById('hrr-display').innerHTML = hrr + " bpm";
// Update Table
var tbody = document.getElementById('zones-body');
tbody.innerHTML = ";
var zones = [
{ name: "Zone 1 (Very Light)", intensity: "50% – 60%", range: z1Min + " – " + z1Max, benefit: "Warm up, recovery, improves overall health." },
{ name: "Zone 2 (Light)", intensity: "60% – 70%", range: z2Min + " – " + z2Max, benefit: "Fat burning, basic endurance, easy conversation." },
{ name: "Zone 3 (Moderate)", intensity: "70% – 80%", range: z3Min + " – " + z3Max, benefit: "Aerobic fitness, improves blood circulation." },
{ name: "Zone 4 (Hard)", intensity: "80% – 90%", range: z4Min + " – " + z4Max, benefit: "Increases max performance capacity (anaerobic)." },
{ name: "Zone 5 (Maximum)", intensity: "90% – 100%", range: z5Min + " – " + z5Max, benefit: "Develops maximum performance and speed." }
];
for (var i = 0; i < zones.length; i++) {
var row = "
" +
"
" + zones[i].name + "
" +
"
" + zones[i].intensity + "
" +
"
" + zones[i].range + "
" +
"
" + zones[i].benefit + "
" +
"
";
tbody.innerHTML += row;
}
}
Understanding Your Minimum Heart Rate and Zones
Whether you are a professional athlete or just starting your fitness journey, understanding your heart rate metrics is crucial for safe and effective training. While many people focus on their "Maximum Heart Rate," knowing your Minimum Heart Rate (typically referring to your Resting Heart Rate) and your minimum effective Training Heart Rate is equally important.
What is "Minimum Heart Rate"?
In the context of fitness and health, "Minimum Heart Rate" usually refers to one of two things:
Resting Heart Rate (RHR): This is your heart rate when you are completely at rest, such as when you first wake up in the morning. A lower RHR typically indicates better cardiovascular fitness and more efficient heart function. For most adults, a normal RHR is between 60 and 100 bpm, though athletes may see numbers as low as 40 bpm.
Minimum Training Threshold: This is the minimum heart rate required to achieve a training effect. Generally, exercise becomes beneficial for the cardiovascular system when your heart rate reaches at least 50% of your heart rate reserve above your resting rate.
How This Calculator Works
This calculator uses the Karvonen Formula, which is widely considered more accurate than standard percentages because it takes your specific Resting Heart Rate into account. The math involves:
Target Zone Calculation:(HRR × Intensity %) + Resting Heart Rate.
Why the Minimum Training Zone Matters
The "Zone 1" displayed in the calculator results represents your minimum training zone. Working out in this zone (50-60% intensity) is vital for:
Recovery: Helping your muscles flush out lactic acid after intense workouts.
Warm-up/Cool-down: Safely transitioning your body into and out of exercise.
Base Building: Establishing a foundational level of fitness without overstressing the body.
Safety Considerations
Before starting any new exercise program, consult with a healthcare provider. If you notice your Resting Heart Rate (minimum heart rate) is consistently high (tachycardia) or extremely low without athletic training (bradycardia) accompanied by dizziness, seek medical advice. The numbers provided by this calculator are estimates based on population averages.