Finding the right bra size is crucial for comfort, support, and confidence. A properly fitting bra can alleviate back and shoulder pain, prevent slippage, and ensure your clothing fits and drapes correctly. This calculator helps estimate your bra size based on two key measurements: your band measurement and your bust measurement.
How to Measure:
It's best to measure over a non-padded bra or no bra at all. Use a soft, flexible measuring tape.
Band Measurement: Wrap the measuring tape snugly around your rib cage, directly under your bust. The tape should be level all the way around and snug, but not constricting. Make sure you can fit one finger underneath the tape. This measurement typically corresponds to the band size number (e.g., 32, 34, 36).
Bust Measurement: Wrap the measuring tape loosely around the fullest part of your bust (usually across the nipples). Keep the tape parallel to the ground and ensure it's not too tight. This measurement is used to determine the cup size.
How the Calculator Works (The Math Behind It):
The calculator uses a common method for estimating bra size:
Band Size:
The calculator takes your Band Measurement directly. Most bra band sizes are in even numbers (e.g., 32, 34, 36). If your measurement is an odd number or falls between two sizes, you might need to round up or down depending on personal preference for snugness. However, for simplicity, we use the direct measurement here as a starting point.
A common adjustment is to add a few inches (often 4-5) to the band measurement if it feels too tight, but the direct measurement is the standard starting point for many online calculators.
Cup Size:
The cup size is determined by the difference between your Bust Measurement and your Band Measurement.
The formula is: Cup Size Difference = Bust Measurement – Band Measurement.
This difference is then translated into a letter:
0 inches difference: AA Cup
1 inch difference: A Cup
2 inches difference: B Cup
3 inches difference: C Cup
4 inches difference: D Cup
5 inches difference: DD (or E) Cup
6 inches difference: DDD (or F) Cup
And so on, typically adding one letter for each additional inch.
Combined Size: The final bra size is the combination of the determined band size and cup size (e.g., 34D).
Important Considerations:
This calculator provides an estimation. Bra sizing can vary significantly between brands, styles (balconette, plunge, push-up, full coverage), and even materials.
Fit is Key: Always try bras on when possible. Pay attention to how the band fits (should be snug and parallel), how the cups accommodate your breast tissue (no gaping or spillage), and how the straps feel (supportive, not digging).
International Sizing: Bra sizes differ across countries. This calculator uses standard US sizing.
Shape Matters: Breast shape can influence fit. Some styles might work better for you than others, even if the calculated size seems correct.
Band vs. Straps: Remember, 80% of your bra's support should come from the band, not the straps. If the band rides up, it's too loose. If the straps dig in excessively, the band might be too loose or the cup too small.
Use this calculator as a starting point for finding a bra that offers the best possible fit and comfort for you.
function calculateBraSize() {
var bandInput = document.getElementById("bandMeasurement");
var bustInput = document.getElementById("bustMeasurement");
var resultDiv = document.getElementById("result");
var braSizeResultSpan = document.getElementById("braSizeResult");
var bandMeasurement = parseFloat(bandInput.value);
var bustMeasurement = parseFloat(bustInput.value);
if (isNaN(bandMeasurement) || bandMeasurement <= 0 || isNaN(bustMeasurement) || bustMeasurement <= 0) {
alert("Please enter valid positive numbers for both band and bust measurements.");
resultDiv.style.display = 'none';
return;
}
if (bustMeasurement = 0 && cupDifference = 1 && cupDifference = 2 && cupDifference = 3 && cupDifference = 4 && cupDifference = 5 && cupDifference = 6 && cupDifference = 7 && cupDifference = 8 && cupDifference = 9 && cupDifference = 10 && cupDifference < 11) {
cupSize = "J";
} else {
// For larger differences, you might need a more complex mapping or simply indicate "Larger Cup"
// This simplified version just continues the pattern.
cupSize = String.fromCharCode(67 + Math.floor(cupDifference) + 1); // Starts after D
}
// Adjust band size for common US sizing (often even numbers)
// If bandMeasurement is odd, we might adjust it to the nearest even number for the band size.
// However, many calculators use the direct measurement. Let's stick to that for simplicity here,
// but add a note in the article about rounding.
var finalBandSize = bandSize;
if (finalBandSize % 2 !== 0) {
// Common practice is to round up or down. For simplicity, we'll take the nearest even.
// Alternatively, some use the direct measurement. Let's use the direct measurement as calculated.
// If we wanted to enforce even numbers: finalBandSize = (bandSize % 2 === 0) ? bandSize : bandSize + 1;
}
var estimatedBraSize = finalBandSize + cupSize;
braSizeResultSpan.textContent = estimatedBraSize;
resultDiv.style.display = 'block';
}