function calculateBraSize() {
var underbustRaw = parseFloat(document.getElementById('underbustMeasurement').value);
var bustRaw = parseFloat(document.getElementById('bustMeasurement').value);
var unit = document.getElementById('measurementUnit').value;
var resultDiv = document.getElementById('braSizeResult');
var underbustError = document.getElementById('underbustError');
var bustError = document.getElementById('bustError');
underbustError.textContent = ";
bustError.textContent = ";
resultDiv.innerHTML = 'Your Bra Size: -';
// Input validation
if (isNaN(underbustRaw) || underbustRaw <= 0) {
underbustError.textContent = 'Please enter a valid positive number for underbust measurement.';
return;
}
if (isNaN(bustRaw) || bustRaw <= 0) {
bustError.textContent = 'Please enter a valid positive number for bust measurement.';
return;
}
if (bustRaw < underbustRaw) {
bustError.textContent = 'Bust measurement cannot be less than underbust measurement.';
return;
}
var underbustInches;
var bustInches;
// Convert to inches if unit is cm
if (unit === 'cm') {
underbustInches = underbustRaw / 2.54;
bustInches = bustRaw / 2.54;
} else {
underbustInches = underbustRaw;
bustInches = bustRaw;
}
// Calculate Band Size (US/UK method: round underbust to nearest even number)
var bandSize = Math.round(underbustInches);
if (bandSize % 2 !== 0) {
bandSize++; // Round up to the nearest even number if odd
}
// Ensure minimum band size (e.g., 28 or 30)
if (bandSize < 28) {
bandSize = 28; // Common minimum band size
}
// Calculate Cup Size Difference
var cupDifference = bustInches – bandSize;
// Determine Cup Letter based on difference (US/UK sizing)
var cupLetters = ["AA", "A", "B", "C", "D", "DD", "DDD/F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P"];
var cupIndex = Math.round(cupDifference); // Each inch difference is roughly one cup size
if (cupIndex = cupLetters.length) {
cupIndex = cupLetters.length – 1; // Cap at the largest defined cup
}
var cupLetter = cupLetters[cupIndex];
resultDiv.innerHTML = 'Your Bra Size: ' + bandSize + cupLetter + ' (US/UK Sizing)';
}
Understanding Your Bra Size: A Comprehensive Guide
Finding the perfect bra can be a transformative experience, offering comfort, support, and confidence. However, many individuals wear the wrong bra size, leading to discomfort and an ill-fitting appearance. Our Bra Size Calculator is designed to help you determine your approximate bra size based on two key measurements.
Why Accurate Bra Sizing Matters
An accurately sized bra does more than just look good; it provides essential support, alleviates back and shoulder pain, and can improve posture. A poorly fitting bra can cause:
Straps digging into shoulders
Band riding up the back
Cups gapping or overflowing
Underwire digging into breast tissue or armpits
Overall discomfort and lack of support
How to Measure for Your Bra Size
To use our calculator effectively, you'll need a soft measuring tape and a mirror. It's best to measure while wearing a non-padded bra or no bra at all.
1. Underbust Measurement (Band Size)
This measurement determines your band size. Stand upright and wrap the measuring tape snugly around your rib cage, directly under your bust. Ensure the tape is level all the way around your back. Breathe out to get the smallest possible measurement. This number, when rounded, will form the basis of your band size.
Example: If your underbust measurement is 30.5 inches (77.5 cm), the calculator will round this to an appropriate band size.
2. Bust Measurement (Cup Size)
This measurement helps determine your cup size. Wrap the measuring tape around the fullest part of your bust, usually across the nipples. Make sure the tape is not too tight and doesn't compress your breasts. Keep the tape level across your back. This measurement, in conjunction with your band size, will determine your cup letter.
Example: If your bust measurement is 34 inches (86.4 cm) and your calculated band size is 32, the difference will help determine your cup letter.
Understanding Band and Cup Sizes (US/UK Sizing)
Bra sizes are typically expressed as a number (the band size) followed by a letter (the cup size), for example, 34C.
Band Size: This number (e.g., 32, 34, 36) corresponds to the measurement around your rib cage. In US/UK sizing, band sizes usually increase in increments of two inches (e.g., 30, 32, 34). Our calculator uses a common method where your underbust measurement is rounded to the nearest even number to determine your band size.
Cup Size: This letter (e.g., A, B, C, D) represents the difference between your bust measurement and your band measurement. Each inch of difference typically corresponds to one cup size. For instance, a 1-inch difference is an A cup, a 2-inch difference is a B cup, and so on.
Important Considerations and Tips for a Perfect Fit
Sister Sizes: Bra sizing is not absolute. Sister sizes are bra sizes where the cup volume remains the same, but the band size and cup letter change. For example, a 34B has a similar cup volume to a 32C or a 36A. If your calculated size feels off, trying a sister size can often help.
Brand Variations: Just like clothing, bra sizes can vary slightly between brands. Use this calculator as a starting point, but be prepared to try on different sizes and styles.
Body Changes: Your bra size can change due to weight fluctuations, pregnancy, hormonal shifts, or even age. It's a good idea to re-measure periodically.
Professional Fitting: While this calculator provides a great estimate, nothing beats a professional bra fitting. Experienced fitters can assess your unique body shape and recommend the best styles and sizes for you.
Comfort is Key: Ultimately, the best bra size is the one that feels most comfortable and supportive for you. The band should be firm but not tight, the cups should encapsulate your breasts without gapping or spilling, and the straps should provide support without digging in.
Use this Bra Size Calculator as your first step towards discovering your ideal fit and enjoying the comfort and confidence that comes with a well-fitting bra!