Heart Rate Zone Calculator Resting Heart Rate

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Heart Rate Zone Calculator (Karvonen Method)

Your Training Zones

Zone Intensity BPM Range
function calculateHRZones() { var age = parseFloat(document.getElementById('userAge').value); var rhr = parseFloat(document.getElementById('restingHR').value); var resultSection = document.getElementById('hr-results-section'); var tableBody = document.getElementById('hr-table-body'); var summary = document.getElementById('hr-summary'); if (isNaN(age) || isNaN(rhr) || age <= 0 || rhr <= 0) { alert("Please enter valid positive numbers for Age and Resting Heart Rate."); return; } // Calculations var maxHR = 220 – age; var hrr = maxHR – rhr; if (hrr <= 0) { alert("Resting Heart Rate cannot be higher than or equal to your calculated Maximum Heart Rate (220 – Age). Please check your inputs."); return; } var zones = [ { name: "Zone 1 (Recovery)", intensity: "50-60%", low: 0.50, high: 0.60, color: "#d1d8e0" }, { name: "Zone 2 (Fat Burn)", intensity: "60-70%", low: 0.60, high: 0.70, color: "#778beb" }, { name: "Zone 3 (Aerobic)", intensity: "70-80%", low: 0.70, high: 0.80, color: "#f7d794" }, { name: "Zone 4 (Anaerobic)", intensity: "80-90%", low: 0.80, high: 0.90, color: "#f3a683" }, { name: "Zone 5 (VO2 Max)", intensity: "90-100%", low: 0.90, high: 1.00, color: "#cf6a87" } ]; var html = ""; for (var i = 0; i < zones.length; i++) { var lowBPM = Math.round((hrr * zones[i].low) + rhr); var highBPM = Math.round((hrr * zones[i].high) + rhr); html += "" + "" + zones[i].name + "" + "" + zones[i].intensity + "" + "" + lowBPM + " – " + highBPM + " BPM" + ""; } tableBody.innerHTML = html; summary.innerHTML = "Estimated Max HR: " + maxHR + " BPM" + "Heart Rate Reserve (HRR): " + hrr + " BPM" + "Note: These calculations use the Karvonen Formula, which considers your fitness level via resting heart rate for more personalized results compared to simple age-based formulas."; resultSection.style.display = "block"; }

Understanding Heart Rate Zones and Resting Heart Rate

Target heart rate zones are ranges of beats per minute (BPM) that help you measure the intensity of your exercise. Unlike basic calculators that only use age, a heart rate zone calculator with resting heart rate uses the Karvonen Formula. This method is considered more accurate because it incorporates your current cardiovascular fitness level.

Why Your Resting Heart Rate (RHR) Matters

Your resting heart rate is the number of times your heart beats per minute while you are at complete rest. For most adults, a healthy RHR is between 60 and 100 BPM. Athletes often have lower RHRs (sometimes in the 40s or 50s) because their hearts are more efficient. By including RHR in the calculation, we determine your Heart Rate Reserve (HRR), which represents the actual range of heart beats available for exertion.

The Five Training Zones Explained

  • Zone 1 (50-60%): Very light intensity. Used for warm-ups, cool-downs, and active recovery.
  • Zone 2 (60-70%): Light intensity. This is the "fat-burning" zone where the body primarily uses stored fat for fuel. It improves basic endurance.
  • Zone 3 (70-80%): Moderate intensity. Improves aerobic capacity and cardiovascular strength. It helps you run or cycle faster for longer periods.
  • Zone 4 (80-90%): High intensity. This is the anaerobic zone. It improves your lactate threshold and speed. You will feel breathless here.
  • Zone 5 (90-100%): Maximum effort. Only sustainable for very short bursts. Used for high-intensity interval training (HIIT) and sprinting.

Realistic Example Calculation

Let's look at a 40-year-old individual with a resting heart rate of 70 BPM:

  1. Max Heart Rate: 220 – 40 = 180 BPM.
  2. Heart Rate Reserve: 180 – 70 = 110 BPM.
  3. Zone 2 (60%) Calculation: (110 * 0.60) + 70 = 136 BPM.
  4. Zone 2 (70%) Calculation: (110 * 0.70) + 70 = 147 BPM.
  5. Result: Their Zone 2 range is 136 to 147 BPM.

Tips for Accuracy

To get the most accurate results, measure your resting heart rate in the morning right after you wake up, before you get out of bed or consume caffeine. Track it for three consecutive days and take the average. As your fitness improves, your RHR will likely drop, so it is important to re-calculate your zones every few months to ensure your training remains effective.

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