Calculate Cardio Heart Rate

Cardio Heart Rate Calculator

Calculate your target heart rate zones using the Karvonen Formula.

Optional (Leave empty for Standard Formula)

Moderate (50%) 70% Max (100%)

Understanding Your Cardio Heart Rate

Whether you are training for a marathon, trying to lose weight, or simply improving your cardiovascular health, understanding your heart rate zones is critical for efficient training. This Cardio Heart Rate Calculator helps you determine the optimal beats per minute (BPM) to target during exercise to maximize your results without overtraining.

Why Calculate Your Heart Rate Zones?

Not all exercise yields the same results. Your heart rate determines the energy source your body uses (carbohydrates vs. fats) and the specific physiological adaptation that occurs. By training in specific "zones," you can tailor your workout to your specific goals:

• Fat Burning: Lower intensity, longer duration exercises where the body relies primarily on fat stores for fuel.
• Cardiovascular Endurance: Moderate intensity that strengthens the heart and lungs.
• Peak Performance: High-intensity intervals that improve speed and VO2 max (maximum oxygen uptake).

The Formulas: Standard vs. Karvonen

This calculator employs two primary methods depending on the data you provide:

1. The Standard Method (Age-Predicted Max)

If you do not know your resting heart rate, the calculator uses the standard formula: 220 – Age = Maximum Heart Rate (MHR). The target zones are then calculated as a straight percentage of your MHR. This provides a general baseline suitable for most beginners.

2. The Karvonen Formula (Heart Rate Reserve)

If you input your Resting Heart Rate (RHR), the calculator uses the Karvonen formula, which is generally considered more accurate for individuals with varying fitness levels. It takes into account your "Heart Rate Reserve" (HRR), which is the difference between your maximum and resting heart rates.

The formula is: Target HR = ((MHR – RHR) × Intensity %) + RHR.

Because fit individuals have lower resting heart rates, this formula ensures that the training intensity is scaled correctly to your specific fitness level, preventing the target from being too low.

Heart Rate Training Zones Explained

Here is a breakdown of the 5 typical training zones calculated above:

• Zone 1 (50-60%): Very Light. Used for warm-ups, cool-downs, and active recovery. It aids in recovery and prepares the body for more intense activity.
• Zone 2 (60-70%): Light (Fat Burn). Often called the "fat-burning zone." At this intensity, the body becomes efficient at metabolizing fat. You should be able to hold a conversation easily.
• Zone 3 (70-80%): Moderate (Aerobic). This is the sweet spot for improving aerobic capacity and endurance. Breathing becomes heavier, but you can still speak in short sentences.
• Zone 4 (80-90%): Hard (Anaerobic). You shift from aerobic to anaerobic metabolism. This zone improves lactate threshold and speed. Sustainable for shorter periods only.
• Zone 5 (90-100%): Maximum. Used for very short bursts (sprinting). This pushes your limit and improves maximum speed and neuromuscular power. Consult a doctor before training here.

How to Measure Your Resting Heart Rate

For the most accurate results using the Karvonen formula, measure your resting heart rate right after waking up in the morning, before getting out of bed. Count your pulse for 60 seconds (or for 15 seconds and multiply by 4). Do this for 3-5 days and take the average.

function calculateCardioHeartRate() { // 1. Get Inputs var ageInput = document.getElementById('chrcAge'); var rhrInput = document.getElementById('chrcRHR'); var intensityInput = document.getElementById('chrcIntensityRange'); var age = parseFloat(ageInput.value); var rhr = parseFloat(rhrInput.value); var intensity = parseFloat(intensityInput.value) / 100; // Convert 70 to 0.7 // 2. Validation if (isNaN(age) || age 120) { alert("Please enter a valid age between 1 and 120."); return; } // 3. Logic Setup var maxHeartRate = 220 – age; var targetHeartRate = 0; var useKarvonen = false; // Check if RHR is valid if (!isNaN(rhr) && rhr > 30 && rhr < 200) { useKarvonen = true; } // 4. Calculate Specific Target if (useKarvonen) { var heartRateReserve = maxHeartRate – rhr; targetHeartRate = (heartRateReserve * intensity) + rhr; document.getElementById('resFormulaName').innerText = "Based on Karvonen Formula (using Resting HR)"; } else { targetHeartRate = maxHeartRate * intensity; document.getElementById('resFormulaName').innerText = "Based on Standard Formula (MHR × Intensity)"; } // 5. Update Highlight Boxes document.getElementById('resMHR').innerText = Math.round(maxHeartRate); document.getElementById('resTarget').innerText = Math.round(targetHeartRate); // 6. Generate Zones Table var tbody = document.getElementById('chrcZoneBody'); tbody.innerHTML = ""; // Clear previous results var zones = [ { name: "Zone 1 (Warm Up)", minPct: 0.50, maxPct: 0.60, color: "#9e9e9e", desc: "Recovery / Warm up" }, { name: "Zone 2 (Fat Burn)", minPct: 0.60, maxPct: 0.70, color: "#4caf50", desc: "Fat Metabolism" }, { name: "Zone 3 (Aerobic)", minPct: 0.70, maxPct: 0.80, color: "#2196f3", desc: "Cardio Endurance" }, { name: "Zone 4 (Anaerobic)", minPct: 0.80, maxPct: 0.90, color: "#ff9800", desc: "Performance / Speed" }, { name: "Zone 5 (Peak)", minPct: 0.90, maxPct: 1.00, color: "#f44336", desc: "Max Effort" } ]; for (var i = 0; i < zones.length; i++) { var z = zones[i]; var minBPM, maxBPM; if (useKarvonen) { // Karvonen Calculation for Zones var hrr = maxHeartRate – rhr; minBPM = (hrr * z.minPct) + rhr; maxBPM = (hrr * z.maxPct) + rhr; } else { // Standard Calculation for Zones minBPM = maxHeartRate * z.minPct; maxBPM = maxHeartRate * z.maxPct; } var row = ""; row += "" + z.name + ""; row += "" + (z.minPct * 100) + "% – " + (z.maxPct * 100) + "%"; row += "" + Math.round(minBPM) + " – " + Math.round(maxBPM) + " BPM"; row += "" + z.desc + ""; row += ""; tbody.innerHTML += row; } // 7. Show Results var resultsDiv = document.getElementById('chrcResults'); resultsDiv.classList.add('active'); // Scroll to results resultsDiv.scrollIntoView({ behavior: 'smooth' }); }