.calc-container { background-color: #f9f9f9; padding: 25px; border-radius: 8px; margin-bottom: 30px; box-shadow: 0 2px 4px rgba(0,0,0,0.05); }
.calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; margin-bottom: 20px; }
.calc-input-group { display: flex; flex-direction: column; }
.calc-label { font-weight: 700; margin-bottom: 8px; color: #d31118; font-size: 14px; text-transform: uppercase; }
.calc-input { padding: 12px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; }
.calc-button { background-color: #d31118; color: white; border: none; padding: 15px 25px; font-size: 18px; font-weight: 700; border-radius: 4px; cursor: pointer; width: 100%; transition: background 0.3s; }
.calc-button:hover { background-color: #b00e14; }
.results-box { margin-top: 25px; display: none; }
.zone-table { width: 100%; border-collapse: collapse; margin-top: 15px; }
.zone-table th, .zone-table td { padding: 12px; text-align: left; border-bottom: 1px solid #eee; }
.zone-table th { background-color: #f2f2f2; font-weight: 700; }
.zone-1 { border-left: 8px solid #919191; }
.zone-2 { border-left: 8px solid #34aadc; }
.zone-3 { border-left: 8px solid #4cd964; }
.zone-4 { border-left: 8px solid #ffcc00; }
.zone-5 { border-left: 8px solid #ff3b30; }
.mhr-display { font-size: 20px; font-weight: bold; text-align: center; margin-bottom: 20px; color: #222; }
@media (max-width: 600px) { .calc-grid { grid-template-columns: 1fr; } }
function calculatePolarZones() {
var age = document.getElementById('userAge').value;
var rhr = document.getElementById('restHR').value;
if (!age || age 0);
var rhrVal = hasRHR ? parseInt(rhr) : 0;
var hrr = mhr – rhrVal;
function getBPM(percentage) {
if (hasRHR) {
// Karvonen: ((MHR – RHR) * %intensity) + RHR
return Math.round((hrr * percentage) + rhrVal);
} else {
// Standard: MHR * %intensity
return Math.round(mhr * percentage);
}
}
document.getElementById('mhrValue').innerHTML = "Estimated Max Heart Rate: " + mhr + " BPM";
document.getElementById('z1range').innerHTML = getBPM(0.50) + " – " + getBPM(0.60) + " bpm";
document.getElementById('z2range').innerHTML = getBPM(0.60) + " – " + getBPM(0.70) + " bpm";
document.getElementById('z3range').innerHTML = getBPM(0.70) + " – " + getBPM(0.80) + " bpm";
document.getElementById('z4range').innerHTML = getBPM(0.80) + " – " + getBPM(0.90) + " bpm";
document.getElementById('z5range').innerHTML = getBPM(0.90) + " – " + mhr + " bpm";
document.getElementById('resultsArea').style.display = 'block';
}
Polar Heart Rate Zones Calculator
Optimize your cardiovascular training by calculating your target heart rate zones based on the Polar intensity scale.
| Zone | Intensity | Range (BPM) |
|---|---|---|
| Zone 1 | Very Light (50-60%) | – |
| Zone 2 | Light (60-70%) | – |
| Zone 3 | Moderate (70-80%) | – |
| Zone 4 | Hard (80-90%) | – |
| Zone 5 | Maximum (90-100%) | – |
Understanding Polar Heart Rate Zones
Training with heart rate zones is the most effective way to measure your effort and ensure you are achieving your fitness goals. Polar utilizes five specific zones based on percentages of your maximum heart rate (MHR). By staying within these zones, you can target specific physiological adaptations, from fat burning to aerobic capacity and peak performance.
The Five Training Zones Explained
- Zone 1: Very Light (50–60% MHR) – Ideal for warm-ups, cool-downs, and active recovery. It improves overall health and helps you recover from harder workouts.
- Zone 2: Light (60–70% MHR) – The "fat-burning" zone. This intensity improves basic endurance and allows your body to become more efficient at oxidizing fat for fuel. You should be able to hold a conversation easily.
- Zone 3: Moderate (70–80% MHR) – The aerobic zone. Training here improves your cardiovascular efficiency and aerobic capacity. It strengthens your heart and lungs.
- Zone 4: Hard (80–90% MHR) – The anaerobic zone. Training at this intensity improves your speed endurance and your body's ability to handle lactic acid. Breathing will be heavy.
- Zone 5: Maximum (90–100% MHR) – Peak performance. This zone is for short bursts of maximum effort, like sprinting or high-intensity interval training (HIIT). It improves your maximal oxygen uptake (VO2 max).
How the Calculation Works
This calculator employs two main methods to determine your zones:
- The Age-Based Formula: It calculates your Maximum Heart Rate using the standard formula (220 – Age).
- The Karvonen Method (Heart Rate Reserve): If you provide your Resting Heart Rate (RHR), the calculator uses the Heart Rate Reserve formula. This is often considered more accurate because it accounts for your current fitness level (a lower resting heart rate usually indicates better cardiovascular fitness).
Practical Example
Consider a 30-year-old individual with a Resting Heart Rate of 60 BPM.
- Max Heart Rate: 220 – 30 = 190 BPM.
- Heart Rate Reserve (HRR): 190 – 60 = 130 BPM.
- Zone 3 (Moderate) Lower Limit: (130 * 0.70) + 60 = 151 BPM.
- Zone 3 (Moderate) Upper Limit: (130 * 0.80) + 60 = 164 BPM.
In this example, to stay in Zone 3, the individual would aim to keep their heart rate between 151 and 164 beats per minute during their workout.
Expert Tip: For the most accurate results, find your true Resting Heart Rate by measuring your pulse for one minute immediately after waking up, before getting out of bed.