Calculating your Maximum Heart Rate (MHR) and factoring in your Resting Heart Rate (RHR) is the most accurate way to define cardiovascular training zones. This calculator primarily uses the Karvonen Method, which determines your target heart rate based on your "Heart Rate Reserve" (HRR). This method is generally considered more personalized than simply taking a percentage of your maximum heart rate because it accounts for your current fitness level via your resting heart rate.
How the Calculation Works
We utilize several formulas to estimate your capabilities:
Standard Formula:220 - Age. The oldest and most common formula, though sometimes criticized for being too generalized.
Tanaka Formula:208 - (0.7 × Age). A revised formula often cited in sports medicine as more accurate for healthy adults.
Heart Rate Reserve (HRR):Max Heart Rate - Resting Heart Rate. This number represents the total range of beats available to you during exercise.
Karvonen Formula:Target HR = (HRR × Intensity%) + Resting HR. This formula ensures that 0% intensity equals your resting state, rather than 0 BPM.
Why Resting Heart Rate Matters
Your Resting Heart Rate is a strong indicator of cardiovascular health. A lower RHR typically implies more efficient heart function and better cardiovascular fitness. For most adults, a normal resting heart rate ranges from 60 to 100 beats per minute. Athletes may see ranges between 40 and 60 BPM. By including this metric in the calculator, we ensure your "Zone 1" or "Warm Up" zone starts at a realistic intensity level relative to your body's baseline.
Training Zones Explained
Zone 1 (Very Light): Used for warm-ups and recovery. Improves overall health and helps recovery.
Zone 2 (Light): The "Fat Burning" zone. Builds basic endurance and burns a higher percentage of calories from fat.
Zone 3 (Moderate): Improves aerobic fitness. The sweet spot for marathon training and cardiovascular endurance.
Zone 4 (Hard): Increases maximum performance capacity. Shifts metabolism to anaerobic energy production.
Zone 5 (Maximum): Athletic performance training. Develops speed and neuromuscular system. Sustainable for only short bursts.
function calculateHeartRate() {
var ageInput = document.getElementById('hr-age');
var rhrInput = document.getElementById('hr-rhr');
var formulaSelect = document.getElementById('hr-formula');
var methodSelect = document.getElementById('hr-method');
var age = parseFloat(ageInput.value);
var rhr = parseFloat(rhrInput.value);
var formula = formulaSelect.value;
var method = methodSelect.value;
// Validation
if (!age || age <= 0) {
alert("Please enter a valid age.");
return;
}
if (!rhr || rhr = mhr) {
alert("Resting Heart Rate cannot be higher than Calculated Max Heart Rate (" + mhr + "). Please check your inputs.");
return;
}
// 2. Calculate Heart Rate Reserve (HRR)
var hrr = mhr – rhr;
// 3. Display Summaries
document.getElementById('result-mhr').innerText = mhr;
document.getElementById('result-rhr').innerText = rhr;
document.getElementById('result-hrr').innerText = hrr;
// 4. Generate Zones
var tbody = document.getElementById('zones-table-body');
tbody.innerHTML = "; // Clear previous results
var zones = [
{ name: "Zone 1", label: "Very Light / Recovery", minPct: 0.50, maxPct: 0.60, color: "zone-1", desc: "Warm up, recovery, health improvement." },
{ name: "Zone 2", label: "Light / Fat Burn", minPct: 0.60, maxPct: 0.70, color: "zone-2", desc: "Basic endurance, fat burning." },
{ name: "Zone 3", label: "Moderate / Aerobic", minPct: 0.70, maxPct: 0.80, color: "zone-3", desc: "Improved aerobic fitness, stamina." },
{ name: "Zone 4", label: "Hard / Anaerobic", minPct: 0.80, maxPct: 0.90, color: "zone-4", desc: "Increases max performance capacity." },
{ name: "Zone 5", label: "Maximum / VO2 Max", minPct: 0.90, maxPct: 1.00, color: "zone-5", desc: "Sprinting, speed, neuromuscular tone." }
];
for (var i = 0; i < zones.length; i++) {
var z = zones[i];
var minBpm, maxBpm;
if (method === 'karvonen') {
// Karvonen: (HRR * intensity) + RHR
minBpm = Math.round((hrr * z.minPct) + rhr);
maxBpm = Math.round((hrr * z.maxPct) + rhr);
} else {
// Max Percent: MHR * intensity
minBpm = Math.round(mhr * z.minPct);
maxBpm = Math.round(mhr * z.maxPct);
}
var row = document.createElement('tr');
row.innerHTML =
'