Zone 2 Heart Rate by Age Calculator

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Zone 2 Heart Rate Calculator

Standard (60-70% of Max HR) Karvonen Formula (Uses Resting HR)

Your Zone 2 Results

Lower Bound

0 BPM

Upper Bound

0 BPM

function calculateZone2() { var age = parseFloat(document.getElementById('userAge').value); var restingHR = parseFloat(document.getElementById('restingHR').value); var method = document.getElementById('calcMethod').value; var resultsDiv = document.getElementById('hr-results'); if (isNaN(age) || age 120) { alert("Please enter a valid age."); return; } var maxHR = 220 – age; var lower, upper; if (method === "karvonen") { if (isNaN(restingHR) || restingHR <= 0) { alert("Karvonen method requires a valid Resting Heart Rate."); return; } var hrr = maxHR – restingHR; lower = Math.round((hrr * 0.60) + restingHR); upper = Math.round((hrr * 0.70) + restingHR); } else { lower = Math.round(maxHR * 0.60); upper = Math.round(maxHR * 0.70); } document.getElementById('lowerBound').innerText = lower + " BPM"; document.getElementById('upperBound').innerText = upper + " BPM"; document.getElementById('maxHRDisplay').innerText = "Estimated Max Heart Rate: " + maxHR + " BPM"; resultsDiv.style.display = "block"; }

What is Zone 2 Heart Rate Training?

Zone 2 heart rate training is often referred to as "base training" or "aerobic endurance training." It is a steady-state intensity where your body primarily uses fat as its main fuel source through aerobic metabolism. In this zone, you should be able to maintain a conversation comfortably—often called the "talk test."

Why Calculate Your Zone 2?

Training in Zone 2 is essential for athletes and fitness enthusiasts for several reasons:

  • Mitochondrial Efficiency: It stimulates the growth and efficiency of mitochondria, the power plants of your cells.
  • Fat Oxidation: It teaches your body to utilize fat stores for energy more efficiently, sparing glycogen for higher intensities.
  • Cardiovascular Health: It strengthens the heart and increases stroke volume without the high recovery cost of HIIT.
  • Faster Recovery: Because it is low intensity, it promotes blood flow and recovery from harder sessions.

How the Calculator Works

This calculator uses two primary methods to determine your target heart rate range:

  1. Standard Method: This is a simple percentage-based approach (60-70%) using the formula 220 – Age to estimate your Maximum Heart Rate (MHR).
  2. Karvonen Formula: This is considered more accurate for individuals with a very low or very high resting heart rate. It calculates the Heart Rate Reserve (HRR) by subtracting your resting heart rate from your max heart rate, then applying the percentages to that reserve.
Pro Tip: For the most accurate results, measure your resting heart rate immediately after waking up while still in bed. Use the average of three consecutive mornings.

Zone 2 Heart Rate Example

For a 40-year-old with a resting heart rate of 60 BPM:

  • Max Heart Rate: 180 BPM
  • Standard Zone 2: 108 – 126 BPM
  • Karvonen Zone 2: 132 – 144 BPM (Note: The Karvonen method often yields higher targets for fit individuals).

Disclaimer: This calculator provides estimates based on general formulas. Heart rate zones can vary significantly based on genetics, fitness level, and medication. Consult with a medical professional before starting a new intensive exercise program.

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