Find your estimated bra size by accurately measuring your underbust and bust. A well-fitting bra provides comfort, support, and can improve posture.
Inches
Centimeters
How to Measure for Your Bra Size:
For the most accurate results, wear a non-padded bra or no bra at all. Use a soft measuring tape and ensure it's level across your back for both measurements.
Underbust Measurement (Band Size):
Stand upright and wrap the measuring tape snugly around your rib cage, directly under your bust.
Make sure the tape is parallel to the floor all the way around your back.
Breathe out to get the smallest measurement. This is your underbust measurement.
Bust Measurement (Cup Size):
Wrap the measuring tape around the fullest part of your bust (usually across the nipples).
Ensure the tape is not too tight and doesn't compress your breast tissue.
Keep the tape level across your back, parallel to the floor.
Understanding Your Bra Size:
A bra size is typically represented by a number (the band size) and a letter (the cup size). These two components work together to provide support and shape.
Band Size: The number (e.g., 32, 34, 36) refers to the circumference of the band around your rib cage. The band provides about 80% of the bra's support, so it should fit snugly without digging in or riding up your back.
Cup Size: The letter (e.g., A, B, C, D) indicates the volume of your breasts. The cups should fully enclose your breast tissue without any gaping, wrinkling, or spilling over the top or sides.
It's important to remember that bra sizing can vary between different brands and styles. This calculator provides a widely accepted method for an initial estimate. For the best fit, always try on bras and adjust based on comfort and how the bra sits on your body.
If your calculated size feels uncomfortable, consider trying "sister sizes." For example, a 34C has a similar cup volume to a 32D (smaller band, larger cup) or a 36B (larger band, smaller cup).
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function calculateBraSize() {
var underBust = parseFloat(document.getElementById("underBustMeasurement").value);
var bust = parseFloat(document.getElementById("bustMeasurement").value);
var unit = document.getElementById("measurementUnit").value;
var resultDiv = document.getElementById("braResult");
if (isNaN(underBust) || isNaN(bust) || underBust <= 0 || bust <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for both measurements.";
return;
}
var underBustInches = underBust;
var bustInches = bust;
if (unit === "cm") {
underBustInches = underBust / 2.54;
bustInches = bust / 2.54;
}
// Calculate Band Size (Modern Method: Snug underbust, round up to nearest even if odd)
// Round to nearest whole inch first, then adjust to nearest even.
var bandSize = Math.round(underBustInches);
if (bandSize % 2 !== 0) { // If odd, round up to next even
bandSize += 1;
}
// Common smallest band size is 28. If calculated is less, default to 28 or warn.
if (bandSize < 28) {
bandSize = 28;
}
// Calculate Cup Size
// The cup difference is between the fullest bust and the *calculated band size*.
var cupDifference = bustInches – bandSize;
var cupLetter = "";
if (cupDifference = 0.5 && cupDifference = 1.5 && cupDifference = 2.5 && cupDifference = 3.5 && cupDifference = 4.5 && cupDifference = 5.5 && cupDifference = 6.5 && cupDifference = 7.5 && cupDifference = 8.5 && cupDifference = 9.5 && cupDifference = 10.5 && cupDifference = 11.5 && cupDifference = 12.5) {
cupLetter = "M (or larger)";
} else {
cupLetter = "Too small for standard cups (consider AA or A)";
}
resultDiv.innerHTML = "
Your Estimated Bra Size:
" +
"Band Size: " + bandSize + "" +
"Cup Size: " + cupLetter + "" +
"Combined Bra Size: " + bandSize + cupLetter + "" +
"This is an estimate based on common sizing conventions. Bra fit can vary by brand and style.";
}