Bra Size Calculator
Enter your underbust and bust measurements in inches or centimeters to see US, UK and EU bra sizes. Published US guides use two different rules for the band, so the calculator shows both, plus the size an EU chart gives. Sizing varies by brand, and the same numbers can fit differently in another style, so use the result as a first size to try on. The calculation runs in your browser, and the page does not send your measurements anywhere.
Around your ribcage, directly under your breasts.
Around the fullest part, with the tape level.
How to use the Bra Size Calculator
- Pick inches or centimeters. A fraction such as 30.5 is fine.
- Measure your underbust: wrap the tape around your ribcage directly under your breasts, level all the way around your back.
- Measure your bust around the fullest part, with the tape level. Hanes and Marlies Dekkers both have you measure wearing a bra.
- Press Calculate Size. You get three rows, each with a US, UK and EU size.
- Before you buy, check the measuring guide of that brand, and start with the row that matches it.
How the calculator gets each size
No inches added: band = underbust, rounded up to the next even inch 4 or 5 inches added: band = underbust to the nearest inch, plus 4 if even or 5 if odd US and UK cup, both rows: bust − band, to the nearest inch, with 0 = AA, 1 = A, 2 = B, 3 = C, 4 = D EU chart: band = underbust to the nearest 5 cm, and bust − band gives the cup, with 10 to 12 cm = AA, 12 to 14 cm = A and one letter for each 2 cm up to H at 26 to 28 cm
No body sets one rule that every brand follows, so the page names its sources, all read on November 3, 2026. The first rule is from Kindred Bravely's measuring guide. The second is from the Hanes size chart on Target, which does not say how to round a fraction of an inch, so the calculator rounds the underbust to the nearest inch, as size.ly's chart does. Both guides count one cup for each inch of bust over band. Neither says how to round that difference, and the calculator rounds it to the nearest inch. The EU row uses the band ranges and overbust table in the Marlies Dekkers size guide. That table runs from A to G, and the AA and H steps come from Wikipedia's article on bra size. A bust exactly on the line between two EU cups counts as the larger cup.
Worked example
Underbust 30 in (76.2 cm), bust 36 in (91.44 cm). No inches added: 30 is already even, so the band is 30. Bust minus band is 6 inches, which gives US 30DDD/F and UK 30E. The chart reads that as EU 65F. With 4 or 5 inches added: 30 is even, so the band is 34. Bust minus band is 2 inches, which gives 34B in the US and UK, and EU 75B on the chart. On the EU chart: 76.2 cm rounds to band 75, and 91.44 − 75 = 16.44 cm falls in C, so the size is EU 75C, or 34C in the US and UK. Hanes's own example, a 32 band and a 35 in bust, comes to 3 inches and a C cup. Kindred Bravely's, a 37 in underbust and a 44 in bust, comes to a 38 band and 6 inches. Kindred Bravely prints that as 38F, and the calculator shows it as US 38DDD/F and UK 38E.
Sources
The calculator and the charts below rest on these pages, all read on November 3, 2026. They are brand guides, a conversion chart site and a reference article, so another brand's chart can differ.
US, UK and EU bra size conversion chart
These tables convert a size printed on one label to the same label in another system. Bands are from the international chart in the Marlies Dekkers size guide. Cup letters are from the Pour Moi conversion chart. Pour Moi starts at A, and the AA row is from Marlies Dekkers.
| EU | US | UK | EU underbust |
|---|---|---|---|
| 60 | 28 | 28 | 58 to 62 cm |
| 65 | 30 | 30 | 63 to 67 cm |
| 70 | 32 | 32 | 68 to 72 cm |
| 75 | 34 | 34 | 73 to 77 cm |
| 80 | 36 | 36 | 78 to 82 cm |
| 85 | 38 | 38 | 83 to 87 cm |
| 90 | 40 | 40 | 88 to 92 cm |
| 95 | 42 | 42 | 93 to 97 cm |
| 100 | 44 | 44 | 98 to 102 cm |
| 105 | 46 | 46 | 103 to 107 cm |
| 110 | 48 | 48 | 108 to 112 cm |
| 115 | 50 | 50 | 113 to 117 cm |
| 120 | 52 | 52 | 118 to 122 cm |
| 125 | 54 | 54 | 123 to 127 cm |
| 130 | 56 | 56 | 128 to 132 cm |
| US | UK | EU | US or UK: bust minus band, to the nearest inch |
|---|---|---|---|
| AA | AA | AA | 0 in |
| A | A | A | 1 in |
| B | B | B | 2 in |
| C | C | C | 3 in |
| D | D | D | 4 in |
| DD/E | DD | E | 5 in |
| DDD/F | E | F | 6 in |
| G | F | G | 7 in |
| H | FF | H | 8 in |
| I | G | J | 9 in |
| J | GG | K | 10 in |
| K | H | L | 11 in |
| L | HH | M | 12 in |
| M | J | N | 13 in |
Where published charts disagree
Above D, the letters depend on the chart. Pour Moi gives US DD/E, DDD/F, G and UK DD, E, F, FF. Marlies Dekkers gives US DD, DDD/E, F and UK DD, E, F, G, with no FF. After H, Pour Moi's EU letters skip to J, while Marlies Dekkers uses I. This calculator uses Pour Moi's letters. Marlies Dekkers' underbust ranges run from 63 to 112 cm. The rows outside them come from Wikipedia's table in its article on bra size, which uses the same 5 cm steps.
Frequently asked questions
Why does the calculator show more than one size?
Because published guides give different answers for the same tape measure. Kindred Bravely takes the underbust as the band. Hanes adds 4 or 5 inches. An underbust of 30 in and a bust of 36 in comes to 30DDD/F by the first rule and 34B by the second, and an EU chart gives 75C. No row is the correct one for everybody, so the page shows all three.
Which row should I start with?
The one that matches the brand you are buying. If its guide adds inches, as the Hanes chart does, use the second row. If its guide takes the underbust as the band, use the first. For a label in EU sizes, use the EU row. Then judge the bra on your body. A 2012 study of 45 women in the journal Ergonomics found that the method it calls traditional overestimated band size and underestimated cup size compared with a best fit by professional criteria, and got less accurate as the band grew. The authors advise learning to assess fit and putting less weight on an absolute size. The abstract does not list the steps of that traditional method, so it cannot settle which of these rows is closer.
Why does bra size vary by brand?
Brands measure and cut differently. Hanes has you measure over your best-fitting bra with the tape snug. Marlies Dekkers has you wear a lightly lined or unpadded bra, pull the tape tight under the bust and subtract 5 cm. This calculator does not subtract those 5 cm, because no other guide read for this page does. Marlies Dekkers also says its body measurements are an indication and do not always apply to every body, and that bras from D up can be designed differently from B and C. Kindred Bravely asks you to check the size chart for each bra.
How do US, UK and EU bra sizes convert?
On the charts, a US or UK band of 34 is EU 75, and each step of 2 is 5 in EU. Cups A to D carry the same letter in all three, and they part after that: on Pour Moi's chart, a US DDD/F is a UK E and an EU F. A chart converts a label to a label. It does not know how you measured, which is why the first row can show EU 65F while the EU chart gives the same body 75C.
What does below AA or above the chart mean?
Below AA means the bust is under the band by more than half an inch, or less than 10 cm over the EU band, so that rule has no cup for those numbers. An underbust of 30 in and a bust of 32 in makes a 34 band, 2 inches above the bust, while the first row gives 30B. Above the chart means 13.5 inches or more on the US and UK rows, or more than 28 cm on the EU row, where the published letters disagree. Brands that make those sizes print their own charts.