A cup letter is not a fixed size. It describes the difference between your bust and your band, so the same letter holds more on a bigger band. These guides explain each UK cup on its own terms.
UK cups use double letters (DD, FF, GG, HH, JJ, KK) that other countries do not. Start with the full order if you are unsure where a letter sits.
From smallest to largest.
What an AA cup measures, how it differs from an A, and styles that sit flat.
Cup Guide A, B and C Cups ExplainedThe one, two and three-inch cups, and why they are different on every band.
Cup Guide D Cup Size GuideWhat a D cup measures, why a 30D and a 38D look nothing alike, and which styles suit it.
Cup Guide What Is an E Cup?A six-inch difference, sold everywhere, and far more ordinary than its reputation.
Cup Guide F Cup Size GuideThe UK F cup, why a US "F" is a different size, and where to find F cups on the high street.
Cup Guide FF Cup Size GuideThe cup between F and G: measurements, international labels and where it is sold.
Cup Guide G Cup Size Guide (UK)What a UK G measures, why a US G is two cups smaller, and what to look for in a bra.
Cup Guide GG Cup and Above: GG, H, HH, J, JJ, KThe upper end of the UK ladder, letter by letter, and who makes each size.
No. In UK sizing E is one cup bigger than DD. The short answer and why it gets confused.
Quick Answer Is DDD the Same as F?In the US, yes. In the UK there is no DDD, and an F is a different size.
Quick Answer Is DD a Big Cup Size?Where DD really sits on the scale, and why a 32DD is smaller than most people think.
Quick Answer What Cup Size Is Considered Large?Why no letter is large in itself, and a fairer way to compare sizes.
Quick Answer What Does a 34DD Look Like?The measurements behind a 34DD and why two people in it can look quite different.
Comparison DD Cup vs E CupHow to tell which of the two you actually need when you are trying bras on.
Every UK band and cup in one printable chart, with a lookup that finds your size from your measurements.
Sister Sizes Sister Size Chart & CalculatorPick your size and see which neighbouring sizes hold the same cup volume on a tighter or looser band.
Conversion UK to US Bra Size ConverterLook up the US label for any UK size, band by band and cup by cup.