How to Calculate My Target Heart Rate Zone

Target Heart Rate Zone Calculator .thr-calculator-container { max-width: 800px; margin: 0 auto; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif; line-height: 1.6; color: #333; } .thr-calc-box { background-color: #f9f9f9; border: 1px solid #e0e0e0; border-radius: 8px; padding: 30px; margin-bottom: 40px; box-shadow: 0 4px 6px rgba(0,0,0,0.05); } .thr-input-group { margin-bottom: 20px; } .thr-input-group label { display: block; margin-bottom: 8px; font-weight: 600; color: #2c3e50; } .thr-input-group input { width: 100%; padding: 12px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; box-sizing: border-box; } .thr-btn { background-color: #e74c3c; color: white; border: none; padding: 15px 30px; font-size: 18px; font-weight: bold; border-radius: 4px; cursor: pointer; width: 100%; transition: background-color 0.3s; } .thr-btn:hover { background-color: #c0392b; } #thr-result { margin-top: 25px; padding: 20px; background-color: #fff; border: 1px solid #ddd; border-radius: 4px; display: none; } .thr-summary { font-size: 1.2em; margin-bottom: 20px; text-align: center; background: #ffebee; padding: 15px; border-radius: 4px; color: #c0392b; font-weight: bold; } .thr-table { width: 100%; border-collapse: collapse; margin-top: 15px; } .thr-table th, .thr-table td { border: 1px solid #eee; padding: 12px; text-align: left; } .thr-table th { background-color: #f1f1f1; font-weight: 700; } .thr-table tr:nth-child(even) { background-color: #fafafa; } .thr-article h2 { color: #2c3e50; border-bottom: 2px solid #e74c3c; padding-bottom: 10px; margin-top: 30px; } .thr-article h3 { color: #34495e; margin-top: 25px; } .thr-article p { margin-bottom: 15px; } .thr-article ul { margin-bottom: 20px; padding-left: 20px; } .thr-article li { margin-bottom: 8px; } .note { font-size: 0.9em; color: #666; font-style: italic; }

Calculate Your Heart Rate Zones

Optional. Enter 0 if unknown. Used for the Karvonen Formula (more accurate).
function calculateZones() { var ageInput = document.getElementById('thr_age'); var rhrInput = document.getElementById('thr_rhr'); var resultDiv = document.getElementById('thr-result'); var age = parseInt(ageInput.value); var rhr = parseInt(rhrInput.value); // Validation if (!age || age 120) { alert("Please enter a valid age between 1 and 120."); return; } if (isNaN(rhr) || rhr 200) { rhr = 0; // Default to 0 if invalid } // Calculations var maxHR = 220 – age; var hrr = maxHR – rhr; // Heart Rate Reserve var useKarvonen = (rhr > 0); // Function to calculate BPM based on percentage function getBPM(percentage) { if (useKarvonen) { // Karvonen Formula: (HRR * %) + RHR return Math.round((hrr * (percentage / 100)) + rhr); } else { // Standard Max HR Formula: MaxHR * % return Math.round(maxHR * (percentage / 100)); } } // Define Zones var z1_min = getBPM(50); var z1_max = getBPM(60); var z2_min = getBPM(60); var z2_max = getBPM(70); var z3_min = getBPM(70); var z3_max = getBPM(80); var z4_min = getBPM(80); var z4_max = getBPM(90); var z5_min = getBPM(90); var z5_max = maxHR; var formulaUsed = useKarvonen ? "Karvonen Formula (Considers Resting HR)" : "Standard Formula (220 – Age)"; var html = '
'; html += 'Estimated Max Heart Rate: ' + maxHR + ' BPM'; html += 'Method: ' + formulaUsed + ''; html += '
'; html += ''; html += ''; html += ''; html += ''; html += ''; html += ''; html += ''; html += ''; html += '
ZoneIntensityTarget Range (BPM)Benefit
Zone 150-60%' + z1_min + ' – ' + z1_max + 'Warm Up / Recovery
Zone 260-70%' + z2_min + ' – ' + z2_max + 'Fat Burning / Endurance
Zone 370-80%' + z3_min + ' – ' + z3_max + 'Aerobic Fitness
Zone 480-90%' + z4_min + ' – ' + z4_max + 'Anaerobic Threshold
Zone 590-100%' + z5_min + ' – ' + z5_max + 'Maximum Effort / Speed
'; resultDiv.innerHTML = html; resultDiv.style.display = "block"; }

How to Calculate My Target Heart Rate Zone

Whether you are training for a marathon, trying to lose weight, or simply maintaining cardiovascular health, understanding your Target Heart Rate (THR) zones is crucial. Training in specific zones allows you to optimize your workouts, preventing overtraining while ensuring you work hard enough to see results.

Why Calculate Heart Rate Zones?

Heart rate training moves away from the idea of "no pain, no gain" and focuses on efficiency. Different intensity levels trigger different metabolic reactions in the body:

  • Fat Burning: Lower intensity zones often utilize fat as a primary fuel source.
  • Cardio Improvement: Moderate intensity strengthens the heart and lungs.
  • Performance: High intensity improves speed and power but requires longer recovery.

The Formulas: Standard vs. Karvonen

Our calculator above utilizes two different methods depending on the data you provide.

1. The Standard Method (Fox Formula)

This is the simplest way to estimate heart rate zones. It relies solely on your age.

Formula: Maximum Heart Rate (MHR) = 220 – Age

The zones are then calculated as straight percentages of this maximum. While easy to use, it assumes a generic profile and may not account for individual fitness levels.

2. The Karvonen Formula

If you input your Resting Heart Rate (RHR) into the calculator, we use the Karvonen method. This is generally considered more accurate for athletes and fitness enthusiasts because it takes your baseline fitness into account.

Formula: Target HR = ((Max HR − Resting HR) × %Intensity) + Resting HR

By including your resting heart rate (the "Heart Rate Reserve"), the zones are tailored to your specific cardiovascular range.

Understanding the 5 Heart Rate Zones

Zone 1: Very Light (50-60%)

This is used for warm-ups, cool-downs, and active recovery. It helps with blood flow and allows your muscles to recover from more intense sessions without adding stress.

Zone 2: Light (60-70%)

Often called the "Fat Burning Zone." In this zone, the body becomes more efficient at oxidizing fat and transporting oxygen. You should be able to hold a conversation easily while exercising in Zone 2.

Zone 3: Moderate (70-80%)

This is the aerobic zone. Training here improves blood circulation and skeletal muscle efficiency. It is the sweet spot for improving general cardiovascular endurance.

Zone 4: Hard (80-90%)

Here you cross the anaerobic threshold. Your body begins producing lactic acid faster than it can clear it. Training in this zone is sustainable for shorter periods and is used to improve speed and lactate tolerance.

Zone 5: Maximum (90-100%)

This is your peak exertion level, sustainable for only very short bursts (like sprinting). It pushes your neuromuscular system to its limit.

How to Find Your Resting Heart Rate

To get the most accurate results from this calculator:

  1. Find your pulse at your wrist or neck immediately after waking up in the morning, before getting out of bed.
  2. Count the beats for 60 seconds (or count for 15 seconds and multiply by 4).
  3. Repeat this for 3 days and take the average.

Disclaimer: This calculator provides estimates based on general formulas. Always consult a physician before starting a new exercise program, especially if you have a history of heart conditions.

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