Determining the correct bra size is crucial for comfort, support, and overall well-being. While professional fittings are recommended, a home calculation can provide a good starting point. This calculator uses a common method to estimate your cup size based on your band and bust measurements.
How it Works:
The core of bra sizing lies in the difference between your bust measurement (around the fullest part of your chest) and your band measurement (around your ribcage, just under your breasts). This difference, when converted into inches, typically corresponds to a cup letter.
Band Measurement: This is the measurement around your ribcage, directly under your bust. It forms the base of the bra and determines the band size (e.g., 32, 34, 36 inches). The calculator assumes this measurement is taken snugly.
Bust Measurement: This is the measurement around the fullest part of your bust, usually over the nipples. It's important to keep the tape measure level and not too tight.
Cup Size Calculation: The difference between your bust measurement and your band measurement is key. A general guideline is:
1 inch difference = A cup
2 inch difference = B cup
3 inch difference = C cup
4 inch difference = D cup
5 inch difference = DD/E cup
And so on, with subsequent inches often corresponding to double letters or larger cup designations depending on the sizing system.
Sizing Systems: Different countries and regions use varying bra sizing systems (US, UK, EU, AU). While the cup difference calculation is similar, the final designation of the cup letter and band size can differ. This calculator provides an estimate based on the selected system.
Important Considerations:
This calculator provides an estimation. Bra fit can be influenced by breast shape, bra construction, and personal preference.
Always try on bras before purchasing if possible.
If you are between sizes, it's often recommended to try both the smaller and larger band size, and the corresponding cup sizes.
For the most accurate fit, consult a professional bra fitter.
function calculateCupSize() {
var bandInput = document.getElementById("bandMeasurement");
var bustInput = document.getElementById("bustMeasurement");
var systemSelect = document.getElementById("braSizeSystem");
var resultDiv = document.getElementById("result");
var resultValueDiv = document.getElementById("result-value");
var resultBandP = document.getElementById("result-band");
var bandMeasurement = parseFloat(bandInput.value);
var bustMeasurement = parseFloat(bustInput.value);
var selectedSystem = systemSelect.value;
// Clear previous results
resultDiv.style.display = 'none';
resultValueDiv.textContent = ";
resultBandP.textContent = ";
// Input validation
if (isNaN(bandMeasurement) || bandMeasurement <= 0) {
alert("Please enter a valid band measurement (a positive number).");
return;
}
if (isNaN(bustMeasurement) || bustMeasurement <= 0) {
alert("Please enter a valid bust measurement (a positive number).");
return;
}
if (bustMeasurement = 1 && cupDifference = 2 && cupDifference = 3 && cupDifference = 4 && cupDifference = 5 && cupDifference = 6 && cupDifference = 7 && cupDifference = 8) {
// For larger differences, it gets more complex and brand-dependent.
// This is a very rough approximation.
var additionalCups = Math.floor(cupDifference – 5); // Start from D/DD difference
if (selectedSystem === "US" || selectedSystem === "UK" || selectedSystem === "AU") {
// US/UK progression can be D, DD, DDD/F, G, H…
if (additionalCups === 1) cupSize = "DD"; // Already handled 5 inch diff as DD
else if (additionalCups === 2) cupSize = "DDD/F"; // Or just F
else if (additionalCups === 3) cupSize = "G";
else if (additionalCups === 4) cupSize = "H";
else cupSize = (additionalCups – 1) + "+"; // Generic for very large
} else { // EU progression: C, D, E, F, G, H…
if (additionalCups === 1) cupSize = "E"; // Already handled 5 inch diff as E
else if (additionalCups === 2) cupSize = "F";
else if (additionalCups === 3) cupSize = "G";
else if (additionalCups === 4) cupSize = "H";
else cupSize = (additionalCups – 1) + "+"; // Generic for very large
}
}
// Display results
resultValueDiv.textContent = cupSize;
resultBandP.textContent = "Band Size: " + bandMeasurement + " (" + selectedSystem + ")";
resultDiv.style.display = 'block';
}