Try two different online bra size calculators with the same measurements and you can get two different sizes back. That's not a bug in one of them — there's no single universal measuring standard, and calculators differ in whether the band is measured above or below the bust and which formula converts the difference into a cup size.
How to measure bra size, the method this calculator uses
This tool uses the traditional US method: round your underbust measurement to the nearest whole number, then add 4 (if even) or 5 (if odd) to get the band size — stated explicitly here rather than left unspecified.
Band and cup size calculator, from two measurements
Enter your underbust (band) and bust (fullest point) measurements in inches or centimeters — the cup size comes from the difference between the two, mapped through the standard letter scale.
Bra size chart, as a starting point only
Studies suggest a large majority of people wear a size that doesn't match any single calculator's output — breast shape, tissue distribution, and brand-specific fit all matter. Use the result as a fitting-room starting point, not a final answer.
