Finding the perfect bra fit is crucial for comfort, support, and overall well-being. A well-fitting bra can alleviate back and shoulder pain, improve posture, and make you feel more confident. However, many people wear the wrong bra size, often due to a misunderstanding of how bras are measured and sized. This Bra Fit Calculator is designed to help you determine your ideal bra size based on simple body measurements.
The Science Behind Bra Sizing
Bra sizing typically involves two primary measurements: the band size and the cup size. These measurements are standardized by lingerie manufacturers, though minor variations can occur between brands.
1. Band Measurement:
The band size is the foundation of your bra's support. It should fit snugly and horizontally around your ribcage, directly under your bust.
How to Measure:
Wear a non-padded, non-minimizer bra, or no bra at all.
Wrap a flexible measuring tape snugly around your ribcage, just below your bust line. Ensure the tape is level all the way around.
Read the measurement in inches.
Calculation: The calculator uses this direct measurement. If the measurement is an odd number, it's common practice to round up to the nearest even number for the band size (e.g., 31 inches becomes 32).
2. Bust Measurement:
The bust measurement is taken around the fullest part of your bust, usually across the nipples.
How to Measure:
While wearing the same type of bra as for the band measurement, wrap the tape measure around the fullest part of your chest.
Ensure the tape is not too tight and is parallel to the floor.
Read the measurement in inches.
3. Calculating the Cup Size:
The cup size is determined by the difference between your bust measurement and your band measurement. This difference indicates how much breast tissue sits away from your ribcage.
The Standard Cup Size Chart:
Difference of 1 inch = A cup
Difference of 2 inches = B cup
Difference of 3 inches = C cup
Difference of 4 inches = D cup
Difference of 5 inches = DD (or E) cup
Difference of 6 inches = DDD (or F) cup
Difference of 7 inches = G cup
And so on, adding one letter for each additional inch.
Note: This is a general guideline, and international sizing can vary.
How Our Calculator Works
Our calculator takes your Band Measurement and Bust Measurement to calculate your estimated bra size. It follows these steps:
Determine Band Size: It takes your band measurement. If it's an odd number, it rounds up to the nearest even number to suggest a band size.
Calculate Cup Size: It subtracts your band measurement from your bust measurement to find the difference in inches. This difference corresponds to a cup size based on the standard chart described above.
Consider Preferences: If you provide your current band and cup size, the calculator will use this as a reference point to refine the suggestion, particularly if your measurements indicate you might be close to a different size.
Common Bra Fit Issues and What They Mean
Band rides up: The band is likely too loose. Try a smaller band size.
Cups gape: The cups are too large for your breast shape or size. Try a smaller cup size.
Breast spills out of the cup (quad-boob): The cups are too small. Try a larger cup size.
Straps dig in: The band might be too loose, causing the straps to carry all the weight. The cups might also be too small, pulling the straps too far back.
Underwire not flat against the sternum: The band or cup size might be incorrect. The underwire should sit comfortably between the breasts.
When to Use This Calculator
This calculator is ideal for:
First-time bra buyers.
Individuals who haven't been professionally fitted in over a year.
Anyone experiencing discomfort or poor fit with their current bras.
Post-pregnancy or weight fluctuations.
Remember, this calculator provides an estimate. The best way to ensure a perfect fit is to try on bras and consult with a professional fitter when possible.
function calculateBraFit() {
var bandMeasurement = parseFloat(document.getElementById("band_measurement").value);
var bustMeasurement = parseFloat(document.getElementById("bust_measurement").value);
var currentBand = document.getElementById("band_size_preference").value;
var currentCup = document.getElementById("cup_size_preference").value;
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = "; // Clear previous results
// Input validation
if (isNaN(bandMeasurement) || isNaN(bustMeasurement) || bandMeasurement <= 0 || bustMeasurement <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for band and bust measurements.";
return;
}
if (bustMeasurement = 1 && bustDifference = 2 && bustDifference = 3 && bustDifference = 4 && bustDifference = 5 && bustDifference = 6 && bustDifference = 7 && bustDifference = 8 && bustDifference = 9 && bustDifference = 10 && bustDifference < 11) {
calculatedCupSize = "J";
} else {
calculatedCupSize = "Larger than J"; // Handle larger differences
}
var finalBandSize = calculatedBandSize;
var finalCupSize = calculatedCupSize;
// Adjust based on current size preference for finer tuning
// This part is heuristic and can be adjusted based on common fitting knowledge
if (currentBand && currentCup) {
var currentBandInt = parseInt(currentBand);
var currentCupIndex = ["AA", "A", "B", "C", "D", "DD", "DDD", "G", "H", "I", "J"].indexOf(currentCup);
if (currentBandInt) {
// If calculated band is smaller than current, and difference is small, stick to current band
if (calculatedBandSize < currentBandInt && (currentBandInt – calculatedBandSize) currentBandInt && (calculatedBandSize – currentBandInt) currentCupIndex && (calculatedCupIndex – currentCupIndex) calculatedCupIndex && (currentCupIndex – calculatedCupIndex) <= 1) {
finalCupSize = currentCup; // Use current cup if it's slightly larger
}
} else if (finalBandSize < currentBandInt && calculatedCupIndex 1) {
// Consider increasing cup size by one step more if band went down significantly
var adjustedCupIndex = currentCupIndex – 1;
if (adjustedCupIndex >= 0 && adjustedCupIndex currentBandInt && calculatedCupIndex > currentCupIndex) {
// If band size went up, cup size might need to go down slightly
if (calculatedCupIndex – currentCupIndex === 1) {
finalCupSize = currentCup;
} else if (calculatedCupIndex – currentCupIndex > 1) {
// Consider decreasing cup size by one step more if band went up significantly
var adjustedCupIndex = currentCupIndex + 1;
if (adjustedCupIndex >= 0 && adjustedCupIndex < ["AA", "A", "B", "C", "D", "DD", "DDD", "G", "H", "I", "J"].length) {
finalCupSize = ["AA", "A", "B", "C", "D", "DD", "DDD", "G", "H", "I", "J"][adjustedCupIndex];
}
}
}
}
}
}
resultDiv.innerHTML = `Your Estimated Bra Size is: ${finalBandSize}${finalCupSize}`;
resultDiv.innerHTML += `Based on measurements: Band ${bandMeasurement}", Bust ${bustMeasurement}"`;
}