Hiit Heart Rate Zone Calculator

HIIT Heart Rate Zone Calculator

Estimated Max Heart Rate

0 BPM

Intensity Zone	Percentage	Target BPM

*Calculated using the Karvonen Formula for more accurate personalized results.

function calculateHIITZones() { var age = parseFloat(document.getElementById('age').value); var rhr = parseFloat(document.getElementById('rhr').value); var resultsArea = document.getElementById('results-area'); var maxHRDisplay = document.getElementById('maxHRDisplay'); var tableBody = document.getElementById('zoneTableBody'); if (isNaN(age) || age <= 0 || isNaN(rhr) || rhr <= 0) { alert("Please enter valid age and resting heart rate values."); return; } // Standard Max HR Formula (Fox) var maxHR = 220 – age; // Heart Rate Reserve var hrr = maxHR – rhr; maxHRDisplay.innerHTML = maxHR + " BPM"; var zones = [ { name: "Recovery / Warm-up", percent: "50% – 60%", low: 0.50, high: 0.60, color: "#e0e0e0" }, { name: "Aerobic / Fat Burn", percent: "60% – 70%", low: 0.60, high: 0.70, color: "#fff9c4" }, { name: "Anaerobic / Threshold", percent: "70% – 80%", low: 0.70, high: 0.80, color: "#ffccbc" }, { name: "HIIT High Intensity", percent: "80% – 90%", low: 0.80, high: 0.90, color: "#ffab91" }, { name: "VO2 Max / Sprint", percent: "90% – 100%", low: 0.90, high: 1.00, color: "#f44336; color: white;" } ]; var tableHtml = ""; for (var i = 0; i < zones.length; i++) { var z = zones[i]; // Karvonen Formula: Target HR = ((Max HR − Rest HR) × %Intensity) + Rest HR var lowBPM = Math.round((hrr * z.low) + rhr); var highBPM = Math.round((hrr * z.high) + rhr); tableHtml += ""; tableHtml += "" + z.name + ""; tableHtml += "" + z.percent + ""; tableHtml += "" + lowBPM + " – " + highBPM + " BPM"; tableHtml += ""; } tableBody.innerHTML = tableHtml; resultsArea.style.display = 'block'; }

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Understanding Your HIIT Heart Rate Zones

High-Intensity Interval Training (HIIT) is one of the most effective ways to improve cardiovascular fitness and accelerate fat loss. However, the "High" in HIIT is specific to your biology. To maximize benefits and avoid overtraining, you must target specific heart rate zones based on your age and cardiovascular health.

What is the Karvonen Formula?

Our calculator uses the Karvonen Formula. Unlike a simple percentage of your maximum heart rate, this method incorporates your Resting Heart Rate (RHR) to calculate your Heart Rate Reserve (HRR). This provides a much more accurate training range because it accounts for your current fitness level. A person with a lower resting heart rate (higher fitness) will have different target ranges than a sedentary individual of the same age.

How to Use Your Results

To get the most out of your HIIT sessions, aim for the following ranges:

• The Work Interval: Your high-intensity bursts should land in the 80% to 95% range. This is where you push your anaerobic threshold and build speed and power.
• The Recovery Interval: Between sprints, your heart rate should drop back down to the 50% to 60% range. This active recovery allows your body to clear lactic acid before the next burst.
• The Sprint Phase: Only the most advanced athletes should aim for the 90%+ zone, and only for very short durations (10–30 seconds).

Practical Example

If you are 30 years old with a resting heart rate of 70 BPM:

1. Max HR: 190 BPM.
2. Heart Rate Reserve: 120 BPM.
3. HIIT Zone (85%): ((120 × 0.85) + 70) = 172 BPM.

In this example, your target for a high-intensity interval would be approximately 172 beats per minute.

Tips for Success

Always start your HIIT session with a 5-10 minute warm-up in the lower zones (50-60%) to prepare your heart and muscles. If you feel dizzy, nauseous, or experience chest pain, stop immediately. Heart rate zones are estimates; always listen to your body's perceived exertion alongside the data.