Bra Size Chart Explained: US, UK, EU and AU Sizes Side by Side

Pick up a bra in a shop and turn over the tag. You might see 34DD, then 75E, then 90E, then 12DD, all printed on the same label for the same garment. Nothing is wrong with the label. Those are four sizing systems describing one bra, and each one counts in its own way. A bra size chart is simply a translation table between them, and once you know the two rules underneath it, how bands are numbered and how cup letters step up, the chart stops looking like a puzzle.

This guide is about reading and converting sizes. If you have not measured yourself yet, start with how to measure bra size, then come back here with your number.

The two parts of every bra size

Every size on the chart has a band and a cup. The band is the number, and it describes the circumference of the band that goes around your ribcage. The cup is the letter, and it describes how much larger the bust is than the band.

The second point trips people up. A cup letter is not a fixed volume. It is a difference. A C cup means roughly three inches between band and bust in the US and UK systems, so the C cup on a 32 band holds less than the C cup on a 38 band. That is why you cannot compare cup letters across different band sizes, and why moving one band size usually means adjusting the letter too, which is the whole idea behind sister sizes.

How band numbers work in each system

• US and UK number bands in inches, in even steps: 30, 32, 34, 36 and up. A 34 band in the US is a 34 band in the UK.
• EU (used across much of continental Europe) numbers bands in centimeters, in 5 cm steps: 65, 70, 75, 80 and up. The number is close to the underbust measurement in centimeters.
• France (and in some charts Spain and Belgium) uses its own band numbers, which run 15 higher than the EU numbers: EU 70 is French 85.
• Australia and New Zealand label bands with dress-size style numbers: 8, 10, 12, 14 and so on. AU 10 corresponds to a 32 band.

Band size conversion chart

Band conversion is the easy half. The steps line up one to one, so if you know your band in one system, you can read it across the row. The cup letters are where systems genuinely diverge.

How cup letters progress, and where they split

All the major systems agree on A, B, C and D. After D, each country continues the alphabet differently:

• The UK uses double letters between single ones: D, DD, E, F, FF, G, GG, H, HH, J, JJ, K. The doubles are full cup sizes in their own right, not half sizes.
• The US commonly goes D, DD, DDD, then G, H, I, J, K. Many makers label the fifth cup “DD/E” and the sixth “DDD/F”, and some use DDDD as well. US lettering beyond D is the least standardized of all.
• The EU uses single letters straight through: D, E, F, G, H, then often J, K, L. Many European labels skip I, reportedly because it is easily mistaken for the number 1.
• Australia generally follows the UK letter sequence, so an Australian DD is the same cup as a UK DD.

Bra size chart for cup conversions

Read each row across. Every cell in a row is the same cup on the same band, just named differently. This is the progression most conversion charts agree on; individual makers may differ by a letter, especially in US sizing.

Notice how quickly the letters drift. By the seventh cup, the same bra could be labeled G in the US, F in the UK and G again in the EU, which is exactly the kind of coincidence that leads people to assume two labels match when they do not. A UK G is two full cup sizes larger than an EU G.

A worked example

Say you wear a UK 34E. To convert it:

1. Find the band row: UK 34 is EU 75, French 90 and Australian 12.
2. Find the cup row: UK E is US DDD (or F), EU F and Australian E.
3. Put them together: US 34DDD or 34F, EU 75F, French 90F, Australian 12E.

Converting the other way works the same. Find each half of the size in its own column, then read across.

Why charts never agree perfectly

If you compare a few conversion charts, you will find small differences between them. There are a few honest reasons for that.

Inches and centimeters do not divide evenly

US and UK cups step up in roughly one-inch increments; European cups step up in roughly 2 cm increments. An inch is 2.54 cm, so the two systems slowly slide against each other. At small sizes the gap is too small to matter. Across many cup sizes it adds up, and charts round it in slightly different ways.

The US has no single standard

Above DD, American makers make their own choices. One might label the sixth cup DDD, another F, another DDDD for the seventh. Some sell larger cups in UK sizing instead, even in the US. When you are shopping US sizes above DD, the maker’s own size chart is the one to trust.

Charts describe labels, not fit

A conversion chart tells you what a label means. It cannot tell you how a particular pattern is cut. Two bras with identical labels can fit differently because of the cup shape, the wire width, the band elastic and the style. A plunge, a balconette and a full-coverage cup in the same size will each feel different, which you can read more about in the bra styles section.

Sizes at the edges of the chart

Most shops stock a fairly narrow middle of the chart, roughly 32 to 38 bands and A to DD cups, so people at either end often assume their size does not exist. It usually does; it is just sold by fewer makers.

At the small end, bands of 28 and below and cups of AA and A are made, though less widely. If you measure into that range, a size from the middle of the chart that “almost works” is often a sign you are wearing a band that is too big with a cup letter that has been bumped up to compensate.

At the large end, UK sizing runs well past the letters in my table, into J, JJ, K and beyond, and bands go above 44. This is one reason many makers who specialize in larger cups use UK letters even when they sell elsewhere: the double-letter sequence leaves room to keep going without the US habit of stacking up Ds. If you wear a large cup in US sizing, it is worth learning your UK equivalent, because it will open up far more choice.

Tips for reading a size label

• Check which system you are reading. A size like 75C is obviously EU. A size like 36F could be US or UK, and those are different cups. Look at the other sizes on the label or the maker’s chart to see which system it uses.
• Do not convert by letter alone. The letter only means something next to its band and its system.
• Convert once, then check the bra. The converted size gets you to the right shelf. Whether the band sits level and the cups lie smoothly is the real test.
• Keep a note of your sizes in each system. If you regularly buy from makers in different countries, writing down your size in each saves you converting every time.

Quick reference: the rules in one place