Heart Rate Zone Calculator Reddit

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Reddit-Recommended Heart Rate Zone Calculator

Based on the Karvonen Formula frequently discussed in r/running and r/fitness

Your Personalized Training Zones

Zone Intensity BPM Range

*Estimated Max HR: BPM | Heart Rate Reserve: BPM

How the Reddit Heart Rate Zone Calculator Works

If you frequent subreddits like r/running, r/cycling, or r/fitness, you've likely seen users debating the best way to calculate training zones. While many generic calculators use the simple "220 minus age" formula, Redditors often recommend the Karvonen Formula.

Why Use the Karvonen Method?

The Karvonen method is superior to basic formulas because it accounts for your Resting Heart Rate (RHR). This determines your Heart Rate Reserve (HRR)—the actual range of beats available for exercise. A marathon runner with a resting pulse of 45 BPM has a different physiological profile than a beginner with a resting pulse of 75 BPM, even if they are the same age.

Understanding the Five Zones

  • Zone 1 (Recovery): 50-60% HRR. Used for active recovery and warming up. You should be able to hold a full conversation easily.
  • Zone 2 (Aerobic/Base): 60-70% HRR. The "Holy Grail" of Reddit training advice. This builds mitochondrial density and endurance. You can speak in full sentences but with slight effort.
  • Zone 3 (Tempo): 70-80% HRR. Improves aerobic capacity. Conversation becomes broken into short sentences.
  • Zone 4 (Threshold): 80-90% HRR. Improves lactate threshold. Very hard effort; you can only manage one or two-word responses.
  • Zone 5 (Anaerobic): 90-100% HRR. Sprints and high-intensity intervals. Maximum effort, non-verbal communication only.

Example Calculation

Imagine a 30-year-old Redditor with a resting heart rate of 60 BPM:

  1. Max HR: 220 – 30 = 190 BPM
  2. HR Reserve: 190 – 60 = 130 BPM
  3. Zone 2 Lower Bound (60%): (130 * 0.60) + 60 = 138 BPM
  4. Zone 2 Upper Bound (70%): (130 * 0.70) + 60 = 151 BPM

This user would aim to keep their heart rate between 138 and 151 BPM for those essential "Zone 2" base-building runs often discussed in the community.

function calculateHeartZones() { var age = parseFloat(document.getElementById('hrAge').value); var rhr = parseFloat(document.getElementById('hrResting').value); var resultDiv = document.getElementById('hrResults'); var tableBody = document.getElementById('hrTableBody'); if (isNaN(age) || isNaN(rhr) || age <= 0 || rhr <= 0) { alert("Please enter valid positive numbers for Age and Resting Heart Rate."); return; } // Calculations var mhr = 220 – age; var hrr = mhr – rhr; if (hrr <= 0) { alert("Resting heart rate cannot be higher than maximum heart rate. Please check your inputs."); return; } var zones = [ { name: "Zone 1", label: "Recovery", low: 0.50, high: 0.60, color: "#e9ecef" }, { name: "Zone 2", label: "Aerobic / Base", low: 0.60, high: 0.70, color: "#d4edda" }, { name: "Zone 3", label: "Tempo", low: 0.70, high: 0.80, color: "#fff3cd" }, { name: "Zone 4", label: "Threshold", low: 0.80, high: 0.90, color: "#ffe5d0" }, { name: "Zone 5", label: "Anaerobic / VO2", low: 0.90, high: 1.00, color: "#f8d7da" } ]; 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 += ""; html += "" + zones[i].name + ""; html += "" + zones[i].label + ""; html += "" + lowBpm + " – " + highBpm + " BPM"; html += ""; } document.getElementById('estMaxHR').innerText = mhr; document.getElementById('estHRR').innerText = hrr; tableBody.innerHTML = html; resultDiv.style.display = "block"; // Smooth scroll to results resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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