Skip to the tool
Real Bra Size Calculator
Menu

Bra Size Calculator UK

Your size on the UK ladder - the one that runs D, DD, E, F, FF, G rather than stacking Ds. Measure in inches or centimetres; no four inches are added to anything.

The six-measurement method of the A Bra That Fits community. The band comes from the snug underbust; the cup from the leaning bust and the loose underbust. The tight underbust does not change your size - it adds a note on how firm a band will feel - so you can leave it out. Implemented independently and not affiliated, so a result can differ from theirs. How to take all six.

Not sure where the tape goes? See how to take both measurements.

If your breasts sit low or are soft, add one more measurement

Try it

Move the measurements and watch the size change

Both drawings are the same body: from the side, and sliced across and seen from above. Drag either measurement and both redraw.

Measurements

One body, two views

from the side
from above
Size
34D
Bust
38"
Across the chest
6.64"
Weight, each
423-879 g

The UK cup ladder, and why it goes so much further

British sizing counts every inch of difference between bust and band, and it gives each one its own label by alternating single and doubled letters:

  • 4 inches → D
  • 5 inches → DD
  • 6 inches → E
  • 7 inches → F
  • 8 inches → FF
  • 9 inches → G
  • 10 inches → GG, and onward through H, HH, J, JJ, K

American sizing labels the same measurements D, DD, DDD and then jumps to G, skipping E and F entirely. That is why a UK G and a US G are two different bodies - nine inches of difference against seven - and why a chart that simply lines up the letters is wrong from the sixth inch onwards.

The conversions that catch people out

Bands are the easy half: a UK 34 is a US 34, because both are the ribcage in inches. The cups are where the money goes astray.

  • UK DD = US DD - the last size the two systems agree on.
  • UK E = US DDD, not US E.
  • UK F = US G.
  • UK FF = US H.
  • UK G = US I.

Ordering a US E when you wear a UK E puts you one full cup letter short, which on a well-fitting band is the difference between a cup that contains the breast and one that cuts across it.

Where the +4 method left British fitting

The four-inch addition is a British invention and it persisted on the high street longer than almost anywhere else. Its effect on UK sizing is specific and measurable: it pushes everyone toward the middle of the size range, so the sizes that dominate high-street stock - 34B, 36B, 36C - are substantially over-represented relative to what people actually measure. The two methods, on one set of tape measurements:

Why your size may look unfamiliar

34Bbecomes30E

A 30" ribcage with a 36" bust, fitted the old way and measured directly. The band drops 2 sizes and the cup climbs 4 letters, because the old method took the cup from a band four inches too big. Same volume. Different garment.

The band and the cup move at the same time, which is why a calculated size can look implausible at first glance. It describes the same body either way.

Full UK conversion tables

Bands first, then the cup ladder against every other system. The UK column is highlighted.

Band sizes

US and UK bands are the same number of inches. Everything else is metric: the EU band is the ribcage measurement in centimetres rounded to the nearest 5, France adds 15 to the EU number, Italy counts those same 5cm steps as 1, 2, 3, and Australia subtracts 22 from the inch band.

USUKEUAU/NZJPFRIT
282860-6075-
303065865801
3232701070852
3434751275903
3636801480954
38388516851005
40409018901056
42429520951107
4444100221001158
4646105241051209

Cup letters

Every system agrees up to D. Above it they split three ways, and this is where almost all conversion errors happen: the UK inserts single letters between its doubles, the US stacks Ds and then jumps to G, and the continental systems just carry on through the alphabet. A UK E is a US DDD, not a US E. Past a 15-inch difference American labelling simply stops, which is why the US column runs out before the others do.

DifferenceUSUKEUAU/NZJPFRIT
1"AAAAAAA
2"BBBBBBB
3"CCCCCCC
4"DDDDDDD
5"DDDDEDDEEE
6"DDDEFEFFF
7"GFGFGGG
8"HFFHFFHHH
9"IGIGIII
10"JGGJGGJJJ
11"KHKHKKK
12"LHHLHHLLL
13"MJMJMMM
14"NJJNJJNNN
15"OKOKOOO
16"-KKPKKPPP
17"-LQLQQQ
18"-LLRLLRRR

Buying in the UK specifically

Two things are genuinely better here than in most markets, and both are worth knowing before you order.

Bands run smaller. UK specialist ranges regularly start at a 28 band, sometimes a 26, where American ranges commonly stop at 32. If your ribcage is under 30 inches, buying UK sizing gets you a band that can actually anchor.

Cups run further. A body that American brands simply do not make for - say ten inches of difference on a 30 band - is an ordinary 30GG in Britain and is stocked as such. This is why people outside the UK with larger cup requirements often end up importing.

Other pages

Questions people actually ask

What comes after DD in UK bra sizes?
E, then F, then FF, then G, GG, H, HH, J, JJ, K. The UK alternates single and doubled letters the whole way up, which is why UK sizing runs so much further into the alphabet than American sizing does for the same body. A UK 32G is nine inches of difference between bust and band; an American 32G is seven.
Is a UK E cup the same as a US E cup?
No, and this is the single most expensive mistake when ordering across the Atlantic. A UK E is six inches of difference, which American sizing calls DDD. Most American brands do not use an E at all - they go D, DD, DDD and then jump to G. So a UK E is a US DDD, a UK F is a US G, and a UK FF is a US H.
Do UK bra sizes use inches or centimetres?
Inches, for both halves of the size. UK band numbers are the ribcage measurement in inches and cup letters step by one inch each, which is why a UK size travels straight across to an American one at the band and only diverges at the cup. Measure in centimetres if that is what your tape gives you - this calculator converts - but the size you end up buying is an inch-based one.
Why do British brands fit differently from each other?
Because UK band elastic and cup depth are not standardised, only the labelling is. The practical consequence is that a size which fits in one house may need a sister size in another, and it is worth knowing which direction a brand runs before ordering. The size this calculator gives you is the one to try first, not a size that will fit universally.
What is the smallest UK band size?
UK specialist brands go down to a 28 band and occasionally a 26, which is one of the genuine advantages of buying in the UK - American ranges frequently stop at 32. If your ribcage measures 29 inches, a 28 band with a bigger cup is a real option here in a way it is not everywhere.
My UK size came out much bigger in the cup than I expected.
That is the expected outcome of not adding four inches. A high-street fitting that made you a 36B is often a 32E on the same tape measurements: the band drops two steps and the cup climbs four letters, because the cup was being measured from a band four inches too large. The volume is the same. The distribution of support is not.