Enter your morning heart rate readings to calculate your true RHR and compare it with standard fitness norms.
Male
Female
* Best measured right after waking up, before getting out of bed.
Calculated Resting Heart Rate
— BPM
Cardiovascular Fitness Level
—
How Fitbit Calculates Resting Heart Rate
Unlike a traditional momentary pulse check, Fitbit calculates your Resting Heart Rate (RHR) using data collected throughout the entire day and night. While you sleep, your heart rate is typically at its lowest. Fitbit combines your sleeping heart rate data with readings taken during periods where you are awake but still and calm.
This method provides a more accurate metric of your overall cardiovascular health than a single spot check, which can be influenced by caffeine, stress, or recent movement.
Why Does My Fitbit Number Differ From My Calculation?
If you use the calculator above and find a discrepancy between your manual average and your Fitbit data, consider the following factors:
Timing: Manual checks are best performed immediately upon waking. Fitbit factors in readings from periods of inactivity throughout the day.
Data Frequency: Fitbit devices measure heart rate continuously (every few seconds), whereas a manual check is a single snapshot.
Algorithm Lag: Fitbit's RHR is often a rolling average or weighted calculation that may not immediately reflect a single night of poor sleep.
Interpreting Your RHR
Resting heart rate is a strong indicator of cardiovascular fitness. Generally, a lower RHR indicates a more efficient heart function and better cardiovascular fitness.
Athletes: Often have an RHR between 40-60 BPM due to high stroke volume.
Average Adults: Typically range between 60-100 BPM.
To lower your resting heart rate over time, focus on consistent aerobic exercise (like running, swimming, or cycling), stress management techniques, and maintaining a healthy sleep schedule. Most users see a decrease in their RHR within 4-8 weeks of starting a consistent cardio program.
function calculateRHR() {
// 1. Get Input Values
var ageInput = document.getElementById('age');
var genderInput = document.getElementById('gender');
var inputs = [
document.getElementById('day1'),
document.getElementById('day2'),
document.getElementById('day3'),
document.getElementById('day4'),
document.getElementById('day5')
];
var resultArea = document.getElementById('result-area');
var rhrDisplay = document.getElementById('rhrResult');
var fitnessDisplay = document.getElementById('fitnessLevel');
var comparisonText = document.getElementById('comparisonText');
// 2. Validation
var age = parseFloat(ageInput.value);
var gender = genderInput.value;
if (isNaN(age) || age 110) {
alert("Please enter a valid age between 10 and 110.");
return;
}
var total = 0;
var count = 0;
var values = [];
for (var i = 0; i 0) {
total += val;
count++;
values.push(val);
}
}
if (count < 1) {
alert("Please enter at least one valid heart rate reading (BPM).");
return;
}
// 3. Calculation
var averageRHR = Math.round(total / count);
// 4. Fitness Level Logic (Simplified Normative Data Table)
var level = "Average";
// Define thresholds based on Gender and Age
// Format: [Athlete, Excellent, Good, Above Avg, Average, Below Avg]
// Anything above "Below Avg" is "Poor"
var thresholds = [];
if (gender === 'male') {
if (age <= 25) thresholds = [55, 61, 65, 69, 73, 81];
else if (age <= 35) thresholds = [54, 61, 65, 70, 74, 81];
else if (age <= 45) thresholds = [56, 62, 66, 70, 75, 82];
else if (age <= 55) thresholds = [57, 63, 67, 71, 76, 83];
else if (age <= 65) thresholds = [56, 61, 67, 71, 75, 81];
else thresholds = [55, 61, 65, 69, 73, 79]; // 65+
} else {
// Female
if (age <= 25) thresholds = [60, 65, 68, 72, 76, 83];
else if (age <= 35) thresholds = [59, 64, 68, 72, 76, 82];
else if (age <= 45) thresholds = [59, 64, 69, 73, 77, 84];
else if (age <= 55) thresholds = [60, 65, 69, 73, 77, 83];
else if (age <= 65) thresholds = [59, 64, 68, 73, 77, 84];
else thresholds = [59, 64, 68, 72, 76, 84]; // 65+
}
if (averageRHR <= thresholds[0]) level = "Athlete";
else if (averageRHR <= thresholds[1]) level = "Excellent";
else if (averageRHR <= thresholds[2]) level = "Good";
else if (averageRHR <= thresholds[3]) level = "Above Average";
else if (averageRHR <= thresholds[4]) level = "Average";
else if (averageRHR <= thresholds[5]) level = "Below Average";
else level = "Poor";
// 5. Display Results
rhrDisplay.innerHTML = averageRHR + " BPM";
fitnessDisplay.innerHTML = level;
// Dynamic styling for fitness level
var color = "#333";
if (level === "Athlete" || level === "Excellent") color = "#2e7d32"; // Green
else if (level === "Good" || level === "Above Average") color = "#1976d2"; // Blue
else if (level === "Average") color = "#f57f17"; // Orange
else color = "#d32f2f"; // Red
fitnessDisplay.style.color = color;
fitnessDisplay.style.border = "2px solid " + color;
comparisonText.innerHTML = "Based on data for " + age + " year old " + gender + "s, a resting heart rate of " + averageRHR + " is considered " + level + ".";
resultArea.style.display = "block";
}