Use this calculator to determine your estimated maximum heart rate (MHR) and your target heart rate zones for exercise, using both the Karvonen method and a simple percentage of MHR method. The Karvonen method is generally considered more accurate as it accounts for your resting heart rate.
Enter 0 or leave blank if unknown; only MHR percentage method will be used.
Understanding Your Heart Rate for Exercise
Your heart rate is a crucial indicator of your body's response to physical activity. Monitoring it during exercise can help you optimize your workouts for various fitness goals, such as improving cardiovascular health, burning fat, or increasing endurance.
Maximum Heart Rate (MHR)
Your Maximum Heart Rate (MHR) is the highest number of beats your heart can achieve during maximal exertion. A commonly used formula to estimate MHR is: 220 – Your Age. While this is a general estimate, it provides a good starting point for calculating target heart rate zones. Individual MHR can vary based on genetics, fitness level, and other factors.
Resting Heart Rate (RHR)
Your Resting Heart Rate (RHR) is the number of times your heart beats per minute while at rest. A lower RHR generally indicates better cardiovascular fitness. You can measure your RHR by taking your pulse first thing in the morning before getting out of bed. A typical RHR for adults ranges from 60 to 100 bpm, but well-trained athletes often have RHRs below 60 bpm.
Target Heart Rate Zones
Target Heart Rate (THR) zones are specific heart rate ranges that correspond to different exercise intensities and fitness benefits. Training within these zones helps you achieve your fitness goals more effectively.
Very Light (50-60% MHR): Warm-up, cool-down, recovery.
Light (60-70% MHR): Fat-burning zone, improves general endurance.
Vigorous (80-90% MHR): Anaerobic zone, improves performance and speed.
Maximum (90-100% MHR): Short bursts, high-intensity interval training (HIIT).
Calculation Methods
There are two primary methods to calculate target heart rate zones:
Percentage of Maximum Heart Rate (MHR) Method:
This is the simpler method. You calculate your MHR (220 – Age) and then multiply it by your desired intensity percentages. For example, if your MHR is 190 bpm and you want to train at 70% intensity, your THR would be 190 * 0.70 = 133 bpm.
Karvonen Method:
The Karvonen method is considered more accurate because it takes into account your Resting Heart Rate (RHR), which reflects your current fitness level. It uses your Heart Rate Reserve (HRR), which is the difference between your MHR and RHR.
Formula:THR = ((MHR - RHR) * Intensity %) + RHR
This method provides a more personalized target heart rate zone, especially for individuals with significantly high or low RHRs.
How to Use Your Target Heart Rate
During exercise, you can monitor your heart rate using a fitness tracker, heart rate monitor, or by manually taking your pulse. Aim to keep your heart rate within your calculated target zone for the majority of your workout to achieve the desired benefits. Always consult with a healthcare professional before starting any new exercise program.
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function calculateHeartRate() {
var age = parseFloat(document.getElementById("age").value);
var restingHeartRate = parseFloat(document.getElementById("restingHeartRate").value);
var intensityLow = parseFloat(document.getElementById("intensityLow").value);
var intensityHigh = parseFloat(document.getElementById("intensityHigh").value);
var resultDiv = document.getElementById("heartRateResult");
var output = "";
// Input validation
if (isNaN(age) || age 120) {
output = "Please enter a valid age (1-120 years).";
resultDiv.innerHTML = output;
return;
}
if (isNaN(intensityLow) || intensityLow 100) {
output = "Please enter a valid low intensity percentage (1-100%).";
resultDiv.innerHTML = output;
return;
}
if (isNaN(intensityHigh) || intensityHigh 100) {
output = "Please enter a valid high intensity percentage (1-100%).";
resultDiv.innerHTML = output;
return;
}
if (intensityLow >= intensityHigh) {
output = "Target Intensity Low must be less than Target Intensity High.";
resultDiv.innerHTML = output;
return;
}
// Calculate Maximum Heart Rate (MHR)
var mhr = 220 – age;
output += "Your Estimated Maximum Heart Rate (MHR): " + mhr + " bpm";
// Check if Resting Heart Rate is valid for Karvonen method
var useKarvonen = false;
if (!isNaN(restingHeartRate) && restingHeartRate > 0 && restingHeartRate < mhr) {
useKarvonen = true;
output += "Your Resting Heart Rate (RHR): " + restingHeartRate + " bpm";
} else if (restingHeartRate === 0 || isNaN(restingHeartRate)) {
output += "Resting Heart Rate not provided or invalid. Only Percentage of MHR method will be used.";
} else if (restingHeartRate >= mhr) {
output += "Invalid Resting Heart Rate. RHR must be less than MHR. Only Percentage of MHR method will be used.";
}
// Calculate Target Heart Rate Zone using Karvonen Method
if (useKarvonen) {
var hrr = mhr – restingHeartRate;
var karvonenLow = Math.round((hrr * (intensityLow / 100)) + restingHeartRate);
var karvonenHigh = Math.round((hrr * (intensityHigh / 100)) + restingHeartRate);
output += "Target Heart Rate Zone (Karvonen Method):";
output += "" + intensityLow + "% – " + intensityHigh + "% Intensity: " + karvonenLow + " – " + karvonenHigh + " bpm";
}
// Calculate Target Heart Rate Zone using Percentage of MHR Method
var mhrLow = Math.round(mhr * (intensityLow / 100));
var mhrHigh = Math.round(mhr * (intensityHigh / 100));
output += "Target Heart Rate Zone (Percentage of MHR Method):";
output += "" + intensityLow + "% – " + intensityHigh + "% Intensity: " + mhrLow + " – " + mhrHigh + " bpm";
resultDiv.innerHTML = output;
}