Pick the system printed on your label first; the cup list changes to that system’s letters.
How the bra size calculator works
BraSizeCalc uses the inch-based method most US and UK brands publish. The band is your underbust rounded to the nearest even inch (modern method), or, if you choose the traditional method, rounded to the nearest inch with 4 added for an even number and 5 for an odd one. The cup is the bust measurement minus the band, rounded to the nearest inch, with one letter per inch. Centimetre measurements are divided by 2.54 first. EU bands are 70 for a 32 and go up 5 for each band size; French bands are EU + 15; Australian bands are the inch band minus 22.
Cup letters by bust minus band
| Difference | US | UK | EU |
|---|---|---|---|
| under ½ in | AA | AA | AA |
| 1 in | A | A | A |
| 2 in | B | B | B |
| 3 in | C | C | C |
| 4 in | D | D | D |
| 5 in | DD | DD | E |
| 6 in | DDD | E | F |
| 7 in | G | F | G |
| 8 in | H | FF | H |
| 9 in | I | G | I |
| 10 in | J | GG | J |
| 11 in | K | H | K |
| 12 in | L | HH | L |
| 13 in | M | J | M |
| 14 in | N | JJ | N |
| 15 in | O | K | O |
Band sizes
| Underbust (in) | Band US/UK | EU | FR | AU |
|---|---|---|---|---|
| 27–29 | 28 | 60 | 75 | 6 |
| 29–31 | 30 | 65 | 80 | 8 |
| 31–33 | 32 | 70 | 85 | 10 |
| 33–35 | 34 | 75 | 90 | 12 |
| 35–37 | 36 | 80 | 95 | 14 |
| 37–39 | 38 | 85 | 100 | 16 |
| 39–41 | 40 | 90 | 105 | 18 |
| 41–43 | 42 | 95 | 110 | 20 |
| 43–45 | 44 | 100 | 115 | 22 |
Brands cut differently, so treat the result as a starting size and check the fit: the band should be level and firm, the centre gore should sit flat and the cups should not gap or spill. Sizes past DD vary most between brands.
Frequently asked questions
What is 75B in US size?
34B. EU 75 is a 34 band and the B cup is the same in every system.
What is a UK 32F in US size?
32G. UK F sits one step after UK E, which is US DDD.
How do Australian bra sizes work?
Australian bands are the inch band minus 22 with UK cup letters, so a 34C is an AU 12C.
Is BraSizeCalc free?
Yes, with no sign-up or ads.
Are my measurements saved or sent anywhere?
They are saved in this browser only and never leave your device.