Enter pregnancy week (5-42) for accurate range analysis.
10 Seconds (Multiply by 6)
15 Seconds (Multiply by 4)
30 Seconds (Multiply by 2)
60 Seconds (Full Minute)
Estimated Fetal Heart Rate
0 BPM
Understanding Fetal Heart Rate Monitoring
Monitoring the fetal heart rate (FHR) is a routine part of prenatal care. It provides vital information about the health and well-being of the fetus. While modern ultrasound machines calculate this automatically, many healthcare providers and parents using home Dopplers count beats manually over a short period to estimate the beats per minute (BPM).
How to Use This Calculator
This tool allows you to convert a manual count of heartbeats into a standard BPM measurement. This is particularly useful if you are listening to a fetal Doppler and counting beats against a stopwatch.
Gestational Age: Enter how many weeks pregnant you are. The normal heart rate range changes significantly as the baby grows.
Counting Duration: Select the time window you used to count the beats (10, 15, 30, or 60 seconds). Shorter windows are faster but slightly less accurate; a full minute is the most accurate.
Beats Counted: Enter the total number of beats you heard during that time window.
Normal Fetal Heart Rate Ranges
The fetal heart usually starts beating around 5-6 weeks of gestation. It starts slow, accelerates until about week 9-10, and then gradually settles into a lower average for the remainder of the pregnancy.
Gestational Age
Average BPM Range
Characteristics
5-6 Weeks
80 – 110 BPM
Heart just starting to beat.
7-9 Weeks
140 – 180 BPM
Rapid acceleration phase.
10-12 Weeks
140 – 170 BPM
Peak heart rate usually occurs here.
13-40 Weeks
110 – 160 BPM
Stabilized range for remainder of pregnancy.
What Do The Numbers Mean?
Normal Range (110-160 BPM): For most of the second and third trimesters, a heart rate between 110 and 160 beats per minute is considered normal.
Bradycardia (< 110 BPM): A sustained heart rate slower than 110 BPM in the late second or third trimester may indicate fetal distress, though it can also be transient or related to maternal medication.
Tachycardia (> 160 BPM): A sustained heart rate higher than 160 BPM might indicate maternal fever, fetal infection, or fetal anemia.
Disclaimer: This calculator is for educational and informational purposes only. It is not a medical device. Always consult with your obstetrician or midwife for professional medical advice and accurate fetal monitoring.
function calculateFHR() {
var weeks = parseInt(document.getElementById('gestationalAge').value);
var duration = parseInt(document.getElementById('countMethod').value);
var beats = parseInt(document.getElementById('beatsCounted').value);
var resultBox = document.getElementById('resultBox');
var bpmDisplay = document.getElementById('bpmResult');
var statusDisplay = document.getElementById('statusResult');
var analysisText = document.getElementById('analysisText');
// Validation
if (isNaN(beats) || beats <= 0) {
alert("Please enter a valid number of beats.");
return;
}
if (isNaN(weeks) || weeks 42) {
alert("Please enter a gestational age between 5 and 42 weeks.");
return;
}
// Calculation
var multiplier = 60 / duration;
var bpm = Math.round(beats * multiplier);
// Determine Normal Range based on Gestational Age
var minNormal = 110;
var maxNormal = 160;
var stageDescription = "";
if (weeks = 7 && weeks = 10 && weeks < 13) {
minNormal = 140;
maxNormal = 170;
stageDescription = "Peak rate phase";
} else {
// 13 weeks onwards
minNormal = 110;
maxNormal = 160;
stageDescription = "Second/Third trimester standard range";
}
// Determine Status
var statusHtml = "";
var analysisMsg = "";
if (bpm < minNormal) {
statusHtml = 'Low (Bradycardia)';
analysisMsg = "The calculated heart rate of " + bpm + " BPM is below the typical average range (" + minNormal + "-" + maxNormal + " BPM) for " + weeks + " weeks. Low heart rates can occur transiently, but persistent low rates should be checked by a doctor.";
} else if (bpm > maxNormal) {
statusHtml = 'High (Tachycardia)';
analysisMsg = "The calculated heart rate of " + bpm + " BPM is above the typical average range (" + minNormal + "-" + maxNormal + " BPM) for " + weeks + " weeks. High heart rates can be caused by maternal activity or fever, but should be monitored.";
} else {
statusHtml = 'Normal Range';
analysisMsg = "The calculated heart rate of " + bpm + " BPM falls within the normal expected range (" + minNormal + "-" + maxNormal + " BPM) for " + weeks + " weeks gestation (" + stageDescription + ").";
}
// Display Results
bpmDisplay.innerHTML = bpm + " BPM";
statusDisplay.innerHTML = statusHtml;
analysisText.innerHTML = analysisMsg;
resultBox.style.display = "block";
}