Maintain this heart rate to maximize efficiency for your selected goal.
185 BPM
Max Heart Rate
115 BPM
Heart Rate Reserve
Fat Burn
Current Zone
Formula Used: The Karvonen Method ((Max HR – Resting HR) × %Intensity) + Resting HR. This provides a more personalized result than standard formulas.
Heart Rate Zones Visualization
Graph shows BPM ranges for different exercise intensities based on your age and resting heart rate.
Detailed Zone Breakdown
Your personalized heart rate zones based on the inputs provided above.
Zone Name
Intensity %
Heart Rate Range (BPM)
Primary Benefit
* Ranges are approximate. Consult a physician before starting exercise.
What is a Target Heart Rate Calculator for Weight Loss?
A target heart rate calculator for weight loss is a specialized tool designed to determine the specific heart rate range where your body burns calories and fat most efficiently. Unlike generic fitness trackers, this calculator uses physiological data—specifically your age and resting heart rate—to define your personal "zones."
For individuals seeking weight loss, finding the "Fat Burning Zone" is critical. This zone typically exists between 60% and 70% of your heart rate reserve. By staying within this range derived by the target heart rate calculator for weight loss, your body prioritizes oxidizing fat as fuel rather than depleting glycogen stores (carbohydrates).
Common misconceptions suggest that the harder you work, the more weight you lose. However, pushing into extremely high heart rate zones (anaerobic) shifts metabolism toward sugar burning and may lead to burnout before significant calories are expended. This tool helps you find the "sweet spot" for sustainable weight reduction.
Target Heart Rate Calculator for Weight Loss Formula
This calculator utilizes the Karvonen Formula, widely regarded by exercise physiologists as the gold standard for determining training zones. It is more accurate than the basic "220 minus age" equation because it accounts for your fitness level via your Resting Heart Rate (RHR).
The Step-by-Step Derivation
Estimate Maximum Heart Rate (MHR): $MHR = 220 – Age$
Scenario: Sarah is 45 years old with a resting heart rate of 80 BPM. She wants to start walking to lose weight but doesn't want to overexert herself. She uses the target heart rate calculator for weight loss to find her Fat Burning Zone (60% intensity).
Max HR: 220 – 45 = 175 BPM
HR Reserve: 175 – 80 = 95 BPM
Calculation: (95 × 0.60) + 80 = 137 BPM
Result: Sarah should aim for approximately 137 BPM during her walks to maximize fat oxidation without exhaustion.
Example 2: The Interval Trainer
Scenario: Mark is 30 years old with a resting heart rate of 60 BPM (athletic). He wants to incorporate "Cardio" intervals (75% intensity) to boost his metabolism for weight loss.
Max HR: 220 – 30 = 190 BPM
HR Reserve: 190 – 60 = 130 BPM
Calculation: (130 × 0.75) + 60 = 157.5 BPM
Result: Mark targets 158 BPM. The target heart rate calculator for weight loss shows this is significantly higher than Sarah's target, reflecting his age and fitness level.
How to Use This Target Heart Rate Calculator for Weight Loss
Follow these steps to ensure accurate results:
Measure Resting Heart Rate: Before getting out of bed in the morning, find your pulse. Count the beats for 60 seconds. Enter this into the "Resting Heart Rate" field.
Enter Age: Input your current age in years. This sets your theoretical ceiling (Max HR).
Select Intensity: Choose "Fat Burning (60-70%)" if your primary goal is weight loss. Choose "Cardio" if you are focusing on endurance.
Read the Result: The large green number is your target BPM.
Monitor: Use a smartwatch or manually check your pulse during exercise to stay near this number.
Key Factors That Affect Target Heart Rate Results
Several variables can influence the numbers produced by a target heart rate calculator for weight loss:
Age: Your maximum heart rate naturally declines as you age, lowering your training zones.
Medications: Beta-blockers and thyroid medications can artificially lower or raise your heart rate, meaning standard formulas may need adjustment by a doctor.
Temperature and Humidity: High heat places stress on the cardiovascular system, increasing your heart rate even at lower intensities. You may hit your target BPM sooner in hot weather.
Hydration Status: Dehydration reduces blood volume, causing the heart to beat faster to pump blood. This can skew your perceived exertion vs. actual heart rate.
Caffeine and Stimulants: Pre-workout supplements or coffee can elevate resting and active heart rates, potentially pushing you out of the fat-burning zone unintentionally.
Fitness Level: As you get fitter, your Resting Heart Rate drops. You must update the calculator periodically to ensure your training zones remain accurate.
Frequently Asked Questions (FAQ)
1. How accurate is the target heart rate calculator for weight loss?
While the Karvonen formula is highly effective for the general population, individual variances exist. It provides a solid baseline (±10-15 beats), but clinical stress tests are the only way to get 100% accuracy.
2. Can I lose weight if I exercise below my target zone?
Yes. Any physical activity burns calories. However, exercising below the zone may require longer duration to achieve the same caloric deficit as a session within the targeted range.
3. Should I aim for the top of the zone or the bottom?
Beginners should aim for the lower end. As your stamina improves, aim for the middle or upper end of the range prescribed by the target heart rate calculator for weight loss.
4. What if my heart rate exceeds the target zone?
If you spike above the zone, slow down. Sustained high-intensity exercise (anaerobic) burns glycogen rather than fat and produces lactic acid, which may limit how long you can exercise.
5. How often should I check my pulse?
If you don't have a wearable monitor, check your pulse every 10-15 minutes during a 45-minute session to ensure you are maintaining intensity.
6. Does the "Fat Burning Zone" really work?
Yes, physiologically. At lower intensities (Zone 2), the body uses oxygen to burn fat for fuel. At higher intensities, it switches to faster-burning carbohydrates. For weight loss, burning fat directly is often preferred, though total calorie burn matters most.
7. Why is Resting Heart Rate required?
Including RHR personalizes the data. A 40-year-old athlete and a 40-year-old sedentary person have the same "Max HR" formulaically, but very different training capacities. RHR bridges that gap.
8. Can I use this calculator for HIIT training?
Yes. For HIIT, you would alternate between the "Peak" zone (80-90%) and the "Moderate" zone (50-60%). You can use the calculator to define the BPM boundaries for both intervals.
// GLOBAL VARIABLES
var ctx; // canvas context
var chartCanvas;
// ZONES CONFIGURATION
var ZONES = [
{ name: "Moderate", minPct: 0.50, maxPct: 0.60, color: "#a8dadc", desc: "Warm Up / Recovery" },
{ name: "Fat Burn", minPct: 0.60, maxPct: 0.70, color: "#28a745", desc: "Weight Loss Optimal" },
{ name: "Cardio", minPct: 0.70, maxPct: 0.80, color: "#457b9d", desc: "Endurance Building" },
{ name: "Peak", minPct: 0.80, maxPct: 0.90, color: "#e63946", desc: "High Performance" }
];
// INITIALIZATION
window.onload = function() {
chartCanvas = document.getElementById("zoneChart");
ctx = chartCanvas.getContext("2d");
calculateHeartRate();
};
function calculateHeartRate() {
// 1. Get Inputs
var ageInput = document.getElementById("inputAge");
var rhrInput = document.getElementById("inputRHR");
var intensitySelect = document.getElementById("inputIntensity");
var age = parseInt(ageInput.value);
var rhr = parseInt(rhrInput.value);
var selectedIntensity = parseFloat(intensitySelect.value);
// 2. Validation
var hasError = false;
if (isNaN(age) || age 100) {
document.getElementById("errorAge").style.display = "block";
hasError = true;
} else {
document.getElementById("errorAge").style.display = "none";
}
if (isNaN(rhr) || rhr 150) {
document.getElementById("errorRHR").style.display = "block";
hasError = true;
} else {
document.getElementById("errorRHR").style.display = "none";
}
if (hasError) return;
// 3. Calculation Logic (Karvonen)
// Max HR = 220 – Age
var maxHR = 220 – age;
// HR Reserve = Max HR – Resting HR
var hrReserve = maxHR – rhr;
// Target HR = (HR Reserve * Intensity) + Resting HR
// We calculate a range for the selected zone? No, the select is a specific 'target' floor usually,
// or we use the select value as the mid-point or floor.
// The dropdown values are 0.5, 0.6, 0.7, 0.8. Let's assume the user wants the specific target at that percentage.
// Actually, let's treat the select value as the "Target Floor" and the next tier as "Ceiling".
// But for the "Main Result", let's give the midpoint of the selected zone.
var zoneIndex = 0;
if(selectedIntensity === 0.6) zoneIndex = 1;
if(selectedIntensity === 0.7) zoneIndex = 2;
if(selectedIntensity === 0.8) zoneIndex = 3;
var zoneMinPct = ZONES[zoneIndex].minPct;
var zoneMaxPct = ZONES[zoneIndex].maxPct;
// Calculate min and max BPM for the selected zone
var bpmMin = Math.round((hrReserve * zoneMinPct) + rhr);
var bpmMax = Math.round((hrReserve * zoneMaxPct) + rhr);
// Target is the average of the zone for display
var targetBPM = Math.round((bpmMin + bpmMax) / 2);
// 4. Update UI
document.getElementById("resultTarget").innerText = targetBPM + " BPM";
document.getElementById("resultMax").innerText = maxHR + " BPM";
document.getElementById("resultReserve").innerText = hrReserve + " BPM";
document.getElementById("resultZone").innerText = ZONES[zoneIndex].name;
// Update Table
updateTable(age, rhr, maxHR, hrReserve, zoneIndex);
// Update Chart
drawChart(age, rhr, maxHR, hrReserve, zoneIndex);
}
function updateTable(age, rhr, maxHR, hrReserve, activeIndex) {
var tbody = document.getElementById("zonesTableBody");
tbody.innerHTML = ""; // clear existing
for (var i = 0; i < ZONES.length; i++) {
var z = ZONES[i];
var minB = Math.round((hrReserve * z.minPct) + rhr);
var maxB = Math.round((hrReserve * z.maxPct) + rhr);
var row = document.createElement("tr");
if (i === activeIndex) {
row.className = "active-row";
}
var rangeStr = minB + " – " + maxB;
var pctStr = (z.minPct * 100) + "% – " + (z.maxPct * 100) + "%";
row.innerHTML = "
" + z.name + "
" +
"
" + pctStr + "
" +
"
" + rangeStr + "
" +
"
" + z.desc + "
";
tbody.appendChild(row);
}
}
function drawChart(age, rhr, maxHR, hrReserve, activeIndex) {
// Clear Canvas
ctx.clearRect(0, 0, chartCanvas.width, chartCanvas.height);
// Dimensions
var width = chartCanvas.width;
var height = chartCanvas.height;
var padding = 40;
var chartW = width – (padding * 2);
var chartH = height – (padding * 2);
// Max Y Value (Max HR + padding)
var yMax = maxHR + 10;
var yMin = rhr – 10;
var yRange = yMax – yMin;
// Draw Axes
ctx.beginPath();
ctx.strokeStyle = "#ccc";
ctx.lineWidth = 2;
ctx.moveTo(padding, padding);
ctx.lineTo(padding, height – padding); // Y Axis
ctx.lineTo(width – padding, height – padding); // X Axis
ctx.stroke();
// Draw Bars
var barWidth = (chartW / ZONES.length) – 20;
for (var i = 0; i < ZONES.length; i++) {
var z = ZONES[i];
var zMinBPM = (hrReserve * z.minPct) + rhr;
var zMaxBPM = (hrReserve * z.maxPct) + rhr;
// Calculate heights
// Y position is relative to yMin
// pixel Y = height – padding – ((value – yMin) / yRange * chartH)
var yPosMax = height – padding – ((zMaxBPM – yMin) / yRange * chartH);
var yPosMin = height – padding – ((zMinBPM – yMin) / yRange * chartH);
var barH = yPosMin – yPosMax;
var xPos = padding + 20 + (i * (barWidth + 20));
// Shadow if active
if (i === activeIndex) {
ctx.fillStyle = "rgba(0,0,0,0.1)";
ctx.fillRect(xPos + 5, yPosMax + 5, barWidth, barH);
}
// Draw Rect
ctx.fillStyle = z.color;
ctx.fillRect(xPos, yPosMax, barWidth, barH);
// Labels
ctx.fillStyle = "#333";
ctx.font = "bold 14px Arial";
ctx.textAlign = "center";
// BPM Label
ctx.fillText(Math.round(zMaxBPM), xPos + (barWidth/2), yPosMax – 5);
ctx.fillText(Math.round(zMinBPM), xPos + (barWidth/2), yPosMin + 15);
// Zone Name
ctx.fillStyle = "#000";
ctx.font = "12px Arial";
ctx.fillText(z.name, xPos + (barWidth/2), height – padding + 20);
}
}
function resetCalculator() {
document.getElementById("inputAge").value = 35;
document.getElementById("inputRHR").value = 70;
document.getElementById("inputIntensity").value = "0.6";
calculateHeartRate();
}
function copyResults() {
var target = document.getElementById("resultTarget").innerText;
var max = document.getElementById("resultMax").innerText;
var zone = document.getElementById("resultZone").innerText;
var age = document.getElementById("inputAge").value;
var text = "Target Heart Rate Calculation:\n" +
"Age: " + age + "\n" +
"Goal Zone: " + zone + "\n" +
"Optimal Target: " + target + "\n" +
"Max Heart Rate: " + max;
// Create temporary text area to copy
var tempInput = document.createElement("textarea");
tempInput.value = text;
document.body.appendChild(tempInput);
tempInput.select();
document.execCommand("copy");
document.body.removeChild(tempInput);
// Visual feedback
var btn = document.querySelector(".btn-copy");
var originalText = btn.innerText;
btn.innerText = "Copied!";
btn.style.backgroundColor = "#28a745";
setTimeout(function() {
btn.innerText = originalText;
btn.style.backgroundColor = "#004a99";
}, 2000);
}