Finding your optimum heart rate zone is the most efficient way to achieve your fitness goals. Whether you want to burn fat, build endurance, or improve cardiovascular health, training at the right intensity is key. Use the calculator below to determine your specific heart rate zones based on your age and resting heart rate.
Measure right after waking up. Optional (improves accuracy).
Estimated Maximum Heart Rate
— BPM
Zone
Intensity
Target Range (BPM)
Benefit
*BPM = Beats Per Minute. Calculated using the Karvonen Formula if RHR is provided.
Understanding Target Heart Rate
Your "optimum" heart rate isn't a single number; it is a range that depends on your specific fitness goal. This range is defined as a percentage of your Maximum Heart Rate (MHR). While the standard formula 220 - Age provides a rough estimate, incorporating your Resting Heart Rate (RHR) using the Karvonen Formula offers a much more personalized and accurate result.
Why accuracy matters: If you overestimate your target zone, you risk burnout or injury. If you underestimate it, you may not trigger the physiological changes needed to improve fitness.
The 5 Heart Rate Zones
To optimize your exercise, identify your goal and train in the corresponding zone:
Zone 1 (50-60%): Very Light. Best for warm-ups, cool-downs, and active recovery. It aids in blood flow and muscle recovery.
Zone 2 (60-70%): Light (Fat Burn). This is the "sweet spot" for burning fat and building basic endurance. The body relies mostly on fat stores for fuel.
Zone 3 (70-80%): Moderate (Aerobic). Increases aerobic capacity and cardiovascular strength. You should be breathing harder but still able to speak in short sentences.
Zone 4 (80-90%): Hard (Anaerobic). Improves high-speed endurance and lactate threshold. This is uncomfortable training where your muscles begin to tire.
Zone 5 (90-100%): Maximum. For short bursts of maximum effort (sprinting). This zone is sustainable for only very short periods.
Formulas Used in Calculation
This calculator utilizes two primary methods depending on the data you provide:
1. The Standard Method (MHR)
If you do not know your resting heart rate, we use the simple age-predicted maximum:
Max Heart Rate = 220 - Age
Example: For a 40-year-old, Max HR is 180 BPM. Zone 2 (60%) would be 108 BPM.
2. The Karvonen Formula (Preferred)
If you enter your Resting Heart Rate, we calculate your Heart Rate Reserve (HRR) for greater precision:
Example: A 40-year-old with a Resting HR of 60. Max HR is 180. HRR is 120. To find 60% intensity: (120 × 0.60) + 60 = 132 BPM.
Notice the difference? The Karvonen method suggests a higher, more appropriate target (132 BPM) compared to the standard method (108 BPM) for fit individuals.
How to Measure Resting Heart Rate
For the best results with this calculator, measure your pulse immediately after waking up, before getting out of bed. Place your index and middle fingers on your neck (carotid artery) or wrist (radial artery) and count the beats for 60 seconds. An average adult RHR is between 60 and 100 BPM, while athletes may be as low as 40-60 BPM.
function calculateZones() {
// Get inputs
var ageInput = document.getElementById('hr_age');
var rhrInput = document.getElementById('hr_rhr');
var displayMax = document.getElementById('display_max_hr');
var zonesBody = document.getElementById('zones_body');
var resultsDiv = document.getElementById('results-container');
var age = parseInt(ageInput.value);
var rhr = parseInt(rhrInput.value);
// Validation
if (!age || age 120) {
alert("Please enter a valid age between 10 and 120.");
return;
}
// Calculate Max HR
var maxHR = 220 – age;
displayMax.innerText = maxHR + " BPM";
// Determine calculation method (Standard or Karvonen)
var useKarvonen = !isNaN(rhr) && rhr > 20 && rhr < maxHR;
var hrr = 0; // Heart Rate Reserve
if (useKarvonen) {
hrr = maxHR – rhr;
}
// Define Zones
var zones = [
{ id: 1, name: "Very Light / Warm Up", minPct: 0.50, maxPct: 0.60, benefit: "Recovery & Warm up" },
{ id: 2, name: "Light / Fat Burn", minPct: 0.60, maxPct: 0.70, benefit: "Basic Endurance & Fat Burning" },
{ id: 3, name: "Moderate / Aerobic", minPct: 0.70, maxPct: 0.80, benefit: "Cardiovascular Fitness" },
{ id: 4, name: "Hard / Anaerobic", minPct: 0.80, maxPct: 0.90, benefit: "High Speed Endurance" },
{ id: 5, name: "Maximum / Peak", minPct: 0.90, maxPct: 1.00, benefit: "Maximum Performance" }
];
var htmlBuilder = "";
for (var i = 0; i < zones.length; i++) {
var zone = zones[i];
var minBpm, maxBpm;
if (useKarvonen) {
// (HRR * %) + RHR
minBpm = Math.round((hrr * zone.minPct) + rhr);
maxBpm = Math.round((hrr * zone.maxPct) + rhr);
} else {
// MaxHR * %
minBpm = Math.round(maxHR * zone.minPct);
maxBpm = Math.round(maxHR * zone.maxPct);
}
htmlBuilder += '