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Bra Size Calculator

Get your US, UK & EU bra size from two measurements.

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How to use

  1. 1.Pick inches or centimeters, then measure your underbust snug around the ribcage and type it in.
  2. 2.Measure your bust across the fullest part with the tape level and enter that number.
  3. 3.Read your estimated size instantly in US, UK and EU — band number plus cup letter.

About Bra Size Calculator

A bra size calculator turns two body measurements — your underbust (band) and your bust (fullest point) — into a band number and a cup letter. Enter both in inches or centimeters and this tool returns your estimated size in the US, UK and EU systems at once, updating as you type. How to measure: wrap a tape snug and level around your ribcage directly under your bust; this underbust reading sets the band. Then measure loosely around the fullest part of your bust with the tape parallel to the floor. Measure braless or in a thin, non-padded bra for the truest numbers. How the size is calculated (modern method): your band is the underbust rounded to the nearest even number, so 32.4 inches becomes a 32 band and an odd 31 rounds to 32. Your cup comes from the difference between bust and band, where roughly every one inch of difference is one cup letter: 1 inch is an A, 2 a B, 3 a C, 4 a D, 5 a DD, 6 a DDD, and so on. A 32-inch underbust with a 36-inch bust is about a 32D. Older US store charts add 4 or 5 inches to the band first; that method gives larger band numbers and smaller cups, which is why calculators sometimes disagree. US vs UK vs EU: band numbers match between the US and UK, which both use inches, and convert to centimeters in the EU — a 34 band equals EU 75 and a 32 equals EU 70. Cup letters are identical up to D, then diverge: a US DD is a UK DD but an EU E, a US DDD is a UK E and an EU F, and a US G is a UK F and an EU G. The same letter can mean a different volume across regions, so always check which system a label uses. Half sizes and fit: if your underbust falls between two even bands, try both the calculated size and its sister size — go down a band and up a cup for a tighter fit, or up a band and down a cup for a looser one. Important: these results are estimates. Real cup and band sizing varies significantly between brands, styles and materials, and bodies change over time. Use this number as a starting point, then try a bra on — the band should sit level and snug and the cups should fully contain the breast without gaps or spillage.

Frequently asked questions

How do I measure my band and bust size?
Wrap a tape snug and level around your ribcage right under your bust for the underbust, which sets the band. Then measure loosely around the fullest part of your bust, keeping the tape parallel to the floor. Measure braless or in a thin, non-padded bra for the most accurate numbers.
How do band and cup size get calculated?
Your band is the underbust measurement rounded to the nearest even number. Your cup is the difference between your bust and band, at roughly one inch per cup letter: a 1-inch difference is an A, 2 inches a B, 3 a C, 4 a D, 5 a DD, and 6 a DDD.
What is the difference between US, UK and EU bra sizes?
Band numbers match in the US and UK and convert to centimeters in the EU, so a 34 band equals EU 75. Cup letters agree up to D, then split: US DD equals UK DD but EU E, and US DDD equals UK E and EU F. The same letter can mean different volumes in different regions.
What if I am between sizes or measure a half size?
The band is rounded to the nearest even number, so half measurements fold into the closest standard band. If you feel between sizes, try the sister size too — go down a band and up a cup for a snugger fit, or up a band and down a cup for a looser one.
Is this bra size calculator accurate?
It gives a solid estimate, but real cup and band sizing varies widely between brands, styles and materials. Treat the result as a starting point and always try a bra on to confirm the fit before buying.

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