28 Bra Size: Every Cup on a 28 Band
28 is the smallest band in common production, and the one the old +4 fitting method erased almost completely. Someone with a 27-29 inch underbust was routinely sold a 32 or 34 band, then told the cup was the problem. The band is now cut properly by British and Polish full-bust houses, and barely at all by American mall brands.
Are you really a 28?
Measure snug and level directly under the bust, with no bra on or a non-padded one, and breathe normally. A reading between 27 and 29 inches (69-74 cm) is a 28 band. Nothing is added to that number: the "+4" rule was written for rigid 1950s fabric and on modern elastic it produces a band about two sizes too loose, which is how the same measurement used to be sold as a 32.
Nothing sits below a 28 in normal production, so a reading under 27 inches means checking the tape rather than the size: it must be level all the way round and snug enough that it does not move when you raise your arms. If you measure 29, start at the 28 anyway. Bands stretch with wear, and a 30 that feels right in the shop is usually loose within weeks.
If the tape and the tag disagree, the calculator settles it in two measurements, and how to measure covers the technique in detail.
Every 28 size, in every system
| Size | UK | EU | FR | AU | JP | KR | Volume |
|---|---|---|---|---|---|---|---|
| 28A | 28A | 60A | 75A | 6A | B60 | B60 | 38 cc |
| 28B | 28B | 60B | 75B | 6B | C60 | C60 | 152 cc |
| 28C | 28C | 60C | 75C | 6C | D60 | D60 | 342 cc |
| 28D | 28D | 60D | 75D | 6D | E60 | E60 | 608 cc |
| 28I | 28G | 60I | 75I | 6G | J60 | J60 | 3078 cc |
Every size in the first column has its own page with sister sizes, a volume comparison and shopping notes. Volumes are estimates from the model on the weight page.
Buying at a 28 band
Expect to shop online and expect the choice to be narrower than any other band on this page. A 28 that exists in a mainstream range is often a vanity-sized 30 with the same wire and the same length of elastic, which defeats the point. Check the flat measurement rather than the tag: a true 28 band measures roughly 24-26 inches unstretched.
The fit problem this band produces most
On a 28 the band is doing almost all the support work with very little circumference to do it in, so a band even slightly too loose fails immediately and visibly. If the back rides up on the loosest hook of a 28, the answer is not a 30 - it is a different brand cutting a firmer 28.
Work through it with the fit problem solver, or read the full list of fit problems if you are not sure which one you have.
Why 28D is not the same size as 42D
A cup letter records the difference between bust and underbust, not a volume, so the same letter grows with the band underneath it. On a 28 band, D works out at roughly 608 cc per cup, against 912 cc for 42D - a difference of about 50% from the same letter. Across every band this site charts:
This is also why sister sizing works: dropping a band and adding a letter keeps the volume roughly constant. See sister sizes explained for the full ladder.
Sister sizes for every 28
If a 28 band rides up, the sister on the tighter band is the one to try; if it digs, go the other way. Both hold roughly the cup volume you already wear.
| Your size | Tighter band (26) | Looser band (30) |
|---|---|---|
| 28A | not charted | not charted |
| 28B | not charted | 30A |
| 28C | not charted | 30B |
| 28D | not charted | 30C |
| 28I | not charted | not charted |
Frequently asked questions
Highlighted bands are this one's sister bands: the same cup volume sits on them one letter up or down. Not sure which band you are? Use the calculator.
Last updated August 2026.