Enter your underbust and bust measurements to get your bra size in UK/India, US and EU sizing, with sister sizes and the fit checks that tell you whether the band and cup are right.
How bra size is calculated
A bra size has two parts. The band comes from the underbust measurement — the tape snug and level directly under the bust — rounded to the nearest even number in inches (UK, US and Indian sizing all use inches for the band). The cup is the difference between the loose bust measurement and that band number: each inch is one cup letter. A 30-inch underbust and 35-inch bust give a 30 band and a 5-inch difference, which is a UK 30DD, a US 30DD and an EU 65E.
Cup letters by country
| Bust − band | UK / India | US | EU |
|---|---|---|---|
| < 1 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 | E | DDD | F |
| 7 in | F | G | G |
| 8 in | FF | H | H |
| 9 in | G | I | I |
| 10 in | GG | J | J |
Band conversion
| UK / US / India | EU | France / Spain | Australia |
|---|---|---|---|
| 28 | 60 | 75 | 6 |
| 30 | 65 | 80 | 8 |
| 32 | 70 | 85 | 10 |
| 34 | 75 | 90 | 12 |
| 36 | 80 | 95 | 14 |
| 38 | 85 | 100 | 16 |
| 40 | 90 | 105 | 18 |
Sister sizes and fit checks
Cup volume depends on the band: a 32D, 34C and 36B hold the same volume. If the band feels tight but the cup fits, go up a band and down a cup; if the band rides up at the back, go down a band and up a cup. A well-fitted bra sits level front to back on the loosest hook, the centre piece lies flat against the sternum, straps carry little weight, and nothing spills at the top or sides.
Models: ZJELL Models portfolios record bust in inches and centimetres, not bra size; keep that figure current and the desk can share your bra size with a client when a lingerie or swimwear brief needs it.
Frequently asked questions
Should I add 4 or 5 inches to my underbust?
That was the method for older, less elastic fabrics. Modern bras are sized from the actual underbust measurement rounded to the nearest even number; adding inches gives a band that is too loose.
How do I measure correctly?
Wear a non-padded bra or none. Underbust: tape snug and level directly beneath the bust, exhale. Bust: tape loose over the fullest point, standing straight. Measure twice.
Why does my size differ between brands?
Cup grading, band stretch and style (balcony, plunge, full cup) all differ. Use the calculated size as a starting point and check the fit points listed above.
What is a sister size?
A size with the same cup volume on a different band — 34C and 36B, for example. Useful when the band fits but the cup does not, or a brand runs small in the band.
Is UK sizing the same as Indian sizing?
Indian brands follow the UK/US inch-based system for the band and mostly the UK cup progression (DD, E, F), though some use US letters above D. Check the brand’s own chart for cups above D.
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