Bra Size Calculator
Estimate your band and cup size in US/CA and EU sizing from your band and bust measurements.
Estimated US/CA Size
36AA
EU Size: 80D
Summary
With a 32" band and 36" bust (a 0" difference), the estimated US/CA size is 36AA — approximately 80D in EU sizing.
Band Size
36
Cup Size
AA
Difference (Bust − Band)
0"
EU Size
80D
Band vs. bust measurement (inches)
How Is Bra Size Determined?
Bra size is estimated from two measurements: the band measurement, taken snugly around the ribcage directly under the bust, and the bust measurement, taken around the fullest part of the bust. The band measurement determines the numeric band size, and the difference between the two measurements determines the cup letter.
Studies commonly cited by bra fitters suggest that anywhere from 70% to 85% of women wear an incorrectly fitted bra, often because sizing isn't standardized between brands — a band that digs in or rides up, or cups that overflow or gap, are common signs that a size needs adjusting even after using a calculator like this one.
The Classic Sizing Method
This calculator uses the traditional band-and-bust method still taught by most fitting guides: round the band measurement to the nearest inch, then add 4 if it's even or 5 if it's odd to get the band size. The cup size is then one letter per inch of difference between the bust and that band size.
Why the Band Adjustment Exists
The "+4/+5" adjustment dates back to a time when bras were built with less stretchy bands and needed extra ease to fit comfortably. Many modern fitting guides now recommend simply rounding the underbust measurement to the nearest even number instead, so don't be surprised if a different calculator or fitter gives you a slightly different band size.
Why Sizes Differ by Country
US, UK, and EU sizing systems all measure the same physical fit differently. EU and French sizing express band size in centimeters rather than inches, and cup letter sequences diverge at larger sizes — a US "DDD" is roughly equivalent to a UK "F" and different again from a French "F," which is why cross-brand and cross-country size charts are so often confusing.
Sister Sizes
Bands and cups scale together: going up one band size while going down one cup letter (or vice versa) often produces a very similar cup volume, called a "sister size." If a calculated size doesn't fit quite right, trying its sister size in the same brand is a common next step before assuming the measurement itself was wrong.
Example — Your Current Inputs
With a 32" band and 36" bust (a 0" difference), the estimated US/CA size is 36AA — approximately 80D in EU sizing.
Additional Example — A 34" Band
A 33" band (odd, so +5) gives a band size of 38. With a 41" bust, the difference is 3 inches, for a cup size of C — resulting in an estimated size of 38C, or roughly 85C in EU sizing.
Frequently Asked Questions
Should I measure over or under my current bra?
Most fitting guides recommend measuring without a bra, or over a thin, unpadded bra, to get the most accurate underlying measurements rather than ones distorted by an ill-fitting current bra.
Why doesn't my calculated size match what I wear?
Sizing varies significantly between brands and even between styles from the same brand, so a calculated size is a starting point for trying on, not a guaranteed fit. Body shape, band stretch, and personal comfort preferences all affect the best real-world fit.
Is a bigger cup letter always a bigger cup?
Only relative to the same band size. A cup letter represents a volume difference from the band, so a "C" cup on a 30 band is physically smaller than a "C" cup on a 38 band, even though the letter is the same.