Find your perfect fit using the standard industry measurement method.
Your Estimated Bra Size:
Note: Sizes may vary by brand. This is a recommended starting point.
How to Measure for Your Correct Bra Size
Wearing the wrong bra size isn't just uncomfortable—it can lead to back pain, poor posture, and skin irritation. Statistics suggest that up to 80% of women are wearing the incorrect size. Our calculator uses the traditional measurement system to help you find a comfortable starting point.
Step 1: Measure Your Underbust
Wrap a measuring tape snugly around your ribcage, directly under your bust. Keep the tape level and firm. If you get an even number, that is your base. If it's an odd number, round up or down based on your comfort, though our calculator handles the standard adjustment for you.
Step 2: Measure Your Bust
Measure around the fullest part of your chest (usually at the nipple line). Hold the tape somewhat loosely—it should be level but not compressing your breast tissue.
Understanding the Calculation
The calculation for bra sizing typically involves two primary components:
The Band Size: This is derived from your underbust measurement. Most manufacturers follow the "Plus 4" rule (adding 4 inches to even measurements and 5 to odd measurements), which provides the band number.
The Cup Size: This is determined by the difference between your bust measurement and your calculated band size. Each inch of difference represents one cup letter.
Bra Size Chart & Differences
Difference (Inches)
Cup Size
0 – 1
AA / A
2
B
3
C
4
D
5
DD (E)
6
DDD (F)
Signs Your Bra Doesn't Fit Properly
If you experience any of the following, it might be time to recalculate and try a different size:
The Band Rides Up: If the back of the bra arches toward your shoulder blades, the band is too large.
Spillage: If breast tissue overflows at the top or sides, the cup size is too small.
Gaping: If there is space between your breast and the cup, the cup size is likely too large.
Slipping Straps: While often a strap adjustment issue, it can also indicate a band that is too large and not providing enough support.
function calculateBraSize() {
var underbust = parseFloat(document.getElementById('underbust').value);
var bust = parseFloat(document.getElementById('bust').value);
var resultDiv = document.getElementById('braResult');
var displaySpan = document.getElementById('braSizeDisplay');
if (isNaN(underbust) || isNaN(bust) || underbust <= 0 || bust <= 0) {
alert('Please enter valid measurements for both fields.');
return;
}
if (bust < underbust) {
alert('Bust measurement should be larger than underbust measurement.');
return;
}
// Step 1: Calculate Band Size
// Standard industry rule: If even, add 4. If odd, add 5.
var bandSize;
var roundedUnderbust = Math.round(underbust);
if (roundedUnderbust % 2 === 0) {
bandSize = roundedUnderbust + 4;
} else {
bandSize = roundedUnderbust + 5;
}
// Step 2: Calculate Cup Size
// Difference between bust and calculated band size
var diff = Math.round(bust – bandSize);
var cups = ["AA", "A", "B", "C", "D", "DD", "DDD", "G", "H", "I", "J", "K"];
var cupResult = "";
if (diff = cups.length) {
cupResult = cups[cups.length – 1] + "+";
} else {
cupResult = cups[diff];
}
// Output
displaySpan.innerHTML = bandSize + cupResult;
resultDiv.style.display = 'block';
// Smooth scroll to result
resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}