How the bra size chart works
A bra size chart is a translation table. Every size has two parts: a band number and a cup letter. The band is the measurement around the ribcage, just under the bust. The cup letter says how much larger the bust is than that band. Each country writes those two facts in its own way, so one bra can carry five different labels.
The chart above starts from one band and cup and shows how each system writes it. Pick a row for the band, a column for the cup, and switch countries. Nothing about the bra changes, only the label.
Reading the band numbers
Band numbers are the easy part, because each system follows a fixed rule.
- US and UK use inches. A 34 band is the same in both countries.
- Australia and New Zealand use dress-size numbers that sit 22 below the inch figure. A 34 band becomes AU 12, and a 32 becomes AU 10.
- Europe uses centimeters in steps of 5. A 34 band is EU 75, a 32 is EU 70, and a 36 is EU 80.
- France, Belgium and Spain add 15 to the EU number. So EU 75 is FR 90.
If you know one band, you can work out the rest in your head. That is rarely true of cups.
Reading the cup letters
Cup letters agree across US, UK and AU up to DD. After that the systems split.
The UK adds double letters: D, DD, E, F, FF, G, GG and onward. The US often repeats the D instead, so the cup that is an E in the UK is a DDD in the US. Above DDD, US brands are not consistent. Some go on to G and H, some write DDDD, so treat any US letter past DDD as a starting point and check the brand’s own chart.
European and French sizing uses single letters in order: A, B, C, D, E, F, G. That means an EU E is a UK DD, and an EU F is a UK E. The letters drift apart as cups get larger, which is why a straight letter-for-letter swap goes wrong.
Australian brands mostly follow UK letters. Some skip the double letters above DD and run straight through E, F, G, so look at the label if a size seems a step off.
One size, five labels
Here are a few worked rows so you can check your reading of the chart:
- US 34C = UK 34C = AU 12C = EU 75C = FR 90C.
- US 36DDD = UK 36E = AU 14E = EU 80F = FR 95F.
- UK 32F = US 32G = EU 70G = FR 85G.
In each case the band and the cup volume stay the same. Only the writing changes.
Cup letters are relative to the band
A cup letter on its own tells you very little. A 30E and a 38E share a letter, but the 38E holds far more, because the cup is measured against a larger band. This is also why one cup volume can appear under several sizes. A 34D, a 32DD and a 36C hold about the same amount. Those are called sister sizes, and they are the first thing to try when a band feels too tight or too loose.
When the chart is not the whole answer
A chart is precise about labels and quiet about fit. Two bras with the same label can fit differently, because brands use different elastic, wire shapes and cup depths. Styles differ too: a plunge and a full-cup bra in the same size will not sit the same way.
So use the chart for what it does well. If you have a size that already fits in one country, the chart gives you the equal size in another. If you do not have a size yet, start with how to measure bra size or the calculator, then come back here to convert. If you are buying for someone else and only know her clothing size, the chart cannot help much. The buying for her guide explains what can.
Sources and method
The band rules and cup order on this page come from the sizing logic used by the calculator, which follows widely published fitting guidance. The about page explains the method and its limits.
Sources & method: sizing rules follow the standard band-and-cup system used by UK, US, AU and EU brands, checked against fitting guides from specialist retailers and fitting communities. How we work.