The theoretical maximum beats per minute your heart can handle.
Fat Burning Zone (60% – 70%)
0 – 0 BPM
Optimal zone for utilizing fat as the primary fuel source. Moderate intensity.
Cardio/Aerobic Zone (70% – 80%)
0 – 0 BPM
Best for improving cardiovascular fitness and burning more total calories. Vigorous intensity.
function calculateZones() {
var ageInput = document.getElementById('thr-age');
var rhrInput = document.getElementById('thr-rhr');
var resultsArea = document.getElementById('thr-results-area');
var resMhr = document.getElementById('res-mhr');
var resFatburn = document.getElementById('res-fatburn');
var resCardio = document.getElementById('res-cardio');
var age = parseFloat(ageInput.value);
var rhr = parseFloat(rhrInput.value);
if (isNaN(age) || age 120) {
alert("Please enter a valid age.");
return;
}
// If RHR is empty or invalid, default to generic calculation or ask user.
// For this calculator, we will default to 0 for RHR in the Karvonen formula
// effectively reverting to standard method, OR we require it.
// Let's assume standard 70 if empty to make it user friendly, but specific.
if (isNaN(rhr) || rhr 150) {
rhr = 70; // fallback average
// Update the input to show the user we used a default
rhrInput.value = 70;
}
// 1. Calculate Max Heart Rate (MHR)
// Standard formula: 220 – Age
var mhr = 220 – age;
// 2. Calculate Heart Rate Reserve (HRR) using Karvonen Formula
// HRR = MHR – Resting Heart Rate
var hrr = mhr – rhr;
// 3. Calculate Zones
// Formula: (HRR * Intensity%) + RHR
// Fat Burn Zone (60% – 70%)
var fatBurnLow = Math.round((hrr * 0.60) + rhr);
var fatBurnHigh = Math.round((hrr * 0.70) + rhr);
// Cardio Zone (70% – 80%)
var cardioLow = Math.round((hrr * 0.70) + rhr); // Overlaps slightly or start at high of prev
var cardioHigh = Math.round((hrr * 0.80) + rhr);
// Display Results
resultsArea.style.display = "block";
resMhr.innerHTML = mhr + " BPM";
resFatburn.innerHTML = fatBurnLow + " – " + fatBurnHigh + " BPM";
resCardio.innerHTML = cardioLow + " – " + cardioHigh + " BPM";
}
Understanding Your Target Heart Rate for Weight Loss
When it comes to losing weight efficiently, simply "moving more" isn't always enough. The intensity of your exercise plays a crucial role in how your body utilizes energy. This Target Heart Rate Calculator helps you identify the specific pulse ranges where your body burns the most fat compared to carbohydrates.
What is the Fat Burning Zone?
The "Fat Burning Zone" typically occurs when your heart rate is between 60% and 70% of your Maximum Heart Rate (MHR). In this zone, the body primarily relies on stored fat for fuel because fat requires oxygen to break down, and at this lower intensity, your body can supply sufficient oxygen to the cells.
While high-intensity workouts burn more calories overall per minute, the percentage of calories coming from fat is higher in this lower intensity zone. This makes it a sustainable and effective zone for long-duration exercises like brisk walking, light jogging, or cycling.
The Karvonen Formula vs. Standard Method
Most basic calculators simply take 220 minus your age to find your maximum heart rate. However, this tool uses the Karvonen Formula, which is considered more accurate for individuals with varying fitness levels because it factors in your Resting Heart Rate (RHR).
Standard Method: Doesn't account for how fit you are currently.
Karvonen Method: Calculates your "Heart Rate Reserve" (HRR), giving you a personalized target range based on your current cardiovascular health.
How to Measure Your Resting Heart Rate
To get the most accurate results from this calculator, input your true Resting Heart Rate. The best time to measure this is:
Right after you wake up in the morning, before getting out of bed.
Find your pulse on your wrist (radial artery) or neck (carotid artery).
Count the beats for exactly 60 seconds, or count for 15 seconds and multiply by 4.
Repeat this for 3 days and take the average for the most precise number.
When to Switch to the Cardio Zone?
The Cardio Zone (70% – 80%) is more intense. While the percentage of fat burned decreases, the total caloric expenditure increases. To maximize weight loss, a combination of long sessions in the Fat Burning Zone and shorter, high-intensity sessions in the Cardio Zone (often called interval training) is generally recommended.