Bra Size Calculator
Find your bra size from two measurements, or four for a more accurate fit on fuller busts, in inches or centimeters. You get US, UK, EU, French and Australian sizes plus your sister sizes.
Bra size calculator
How to measure your bra size
- Underbust (band): wearing a non-padded bra or none, wrap the tape snugly around your ribcage right under the bust, level all the way round, and breathe out.
- Bust: measure loosely around the fullest part without squeezing. For the detailed method, also measure leaning forward at 90° and lying on your back; the average better captures soft or fuller breast tissue.
- Band = underbust rounded to the nearest inch, then up to the next even number. Cup = bust − band: each inch is one cup size.
| Bust − band | US cup | UK cup |
|---|---|---|
| 0 in | AA | AA |
| 1 in | A | A |
| 2 in | B | B |
| 3 in | C | C |
| 4 in | D | D |
| 5 in | DD / E | DD |
| 6 in | DDD / F | E |
| 7 in | G | F |
| 8 in | H | FF |
| 9 in | I | G |
Example: underbust 32 in, bust 36 in: band 32, difference 4 in, so 32D in the US and UK, 70D in EU sizing (75D in France).
Bra calculator: sister sizes and fit checks
Cup volume depends on the band, so 32D, 34C and 30DD hold about the same volume. If a band rides up, go down a band and up a cup (34C to 32D); if it's tight but the cups fit, go up a band and down a cup. A good fit: the band is level and does most of the support on the loosest hook, the center gore sits flat against the breastbone, and the cups don't gap or spill.
Sizing differs between brands, especially above DD where US brands use DDD/F, G, H and UK brands use E, F, FF, G, GG. Use the result as a starting size to try on, not a final answer.
Common questions
How do I calculate my bra size?
Band = snug underbust rounded up to an even number. Cup = bust − band in inches: 1 = A, 2 = B, 3 = C, 4 = D, 5 = DD.
What bra size is 32 underbust and 36 bust?
32D in US and UK sizing.
What are sister sizes?
Sizes with the same cup volume: go down a band and up a cup, or up a band and down a cup. 34C = 32D = 36B.
Is a US DDD the same as a UK E?
Yes: a 6-inch difference is DDD (or F) in many US brands and E in UK sizing.
Should I add inches to my band measurement?
Not with the modern method. The old "+4 inches" rule usually gives a band that is too big.
Sources
- Wood, Cameron & Fitzgerald (2008), Chiropractic & Osteopathy: Breast size, bra fit and thoracic pain
- European standard EN 13402 clothing size designation (overview)
Related
General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.