Heart Rate Levels Calculator

Heart Rate Levels & Training Zone Calculator

Your Target Heart Rate Zones

Based on the Karvonen Formula (Heart Rate Reserve method).

Level / Zone	Intensity	Range (BPM)

function calculateHRZones() { var age = parseFloat(document.getElementById('age').value); var rhr = parseFloat(document.getElementById('restingHR').value); var resultsArea = document.getElementById('results-area'); var tableBody = document.getElementById('hr-table-body'); var maxDisplay = document.getElementById('max-hr-display'); if (isNaN(age) || age 120) { alert('Please enter a valid age.'); return; } if (isNaN(rhr) || rhr 120) { alert('Please enter a realistic resting heart rate (usually 40-100 BPM).'); return; } var maxHR = 220 – age; var hrr = maxHR – rhr; var zones = [ { name: "Zone 1 (Very Light)", range: "50% – 60%", min: 0.50, max: 0.60, color: "#d1d8e0" }, { name: "Zone 2 (Light)", range: "60% – 70%", min: 0.60, max: 0.70, color: "#a5d6a7" }, { name: "Zone 3 (Moderate)", range: "70% – 80%", min: 0.70, max: 0.80, color: "#fff59d" }, { name: "Zone 4 (Hard)", range: "80% – 90%", min: 0.80, max: 0.90, color: "#ffcc80" }, { name: "Zone 5 (Maximum)", range: "90% – 100%", min: 0.90, max: 1.00, color: "#ef9a9a" } ]; var html = ""; for (var i = 0; i < zones.length; i++) { var z = zones[i]; var lower = Math.round((hrr * z.min) + rhr); var upper = Math.round((hrr * z.max) + rhr); html += ""; html += "" + z.name + ""; html += "" + z.range + ""; html += "" + lower + " – " + upper + " BPM"; html += ""; } tableBody.innerHTML = html; maxDisplay.innerHTML = "Estimated Maximum Heart Rate: " + maxHR + " BPM"; resultsArea.style.display = "block"; }

Understanding Heart Rate Levels

Heart rate levels, or training zones, are ranges of heartbeats per minute (BPM) that indicate the intensity of physical activity. Monitoring these zones allows athletes and fitness enthusiasts to tailor their workouts toward specific goals, such as fat loss, cardiovascular endurance, or peak athletic performance.

The 5 Training Zones Explained

• Zone 1 (50-60%): Recovery & Health. Best for warm-ups, cool-downs, and improving overall health. It helps with recovery and metabolic efficiency.
• Zone 2 (60-70%): Aerobic Base. Often called the "Fat Burning Zone." It builds basic endurance and burns the highest percentage of calories from fat.
• Zone 3 (70-80%): Aerobic Power. Improves cardiovascular capacity and respiratory efficiency. This is the "moderate" intensity where you can still talk but only in short sentences.
• Zone 4 (80-90%): Anaerobic Threshold. Enhances high-speed endurance. This level increases the body's ability to handle lactic acid buildup.
• Zone 5 (90-100%): Maximum Effort. Reserved for short bursts of high-intensity interval training (HIIT) or sprinting. This improves maximum power and speed.

Calculation Method: The Karvonen Formula

This calculator uses the Karvonen Formula, which is considered more accurate than simple age-based formulas because it incorporates your Resting Heart Rate (RHR). By calculating the Heart Rate Reserve (Max HR – Resting HR), the zones are personalized to your current fitness level.

Real-World Example

Imagine a 40-year-old with a resting heart rate of 70 BPM:

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

Disclaimer: This calculator provides estimates based on standard formulas. Consult a medical professional before beginning any high-intensity exercise program, especially if you have underlying health conditions.