A 28B fits an underbust of 23 to 24 inches with a bust one to two inches larger. Among the four sizes on the 28 band it is the fortunate one: its band-up sister is 30A, and 30A is where most stocked ranges begin.
Not sure it is your size? The bra size calculator turns two measurements into an answer, sister sizes included.
What does a 28B measure?
Band first. Take the underbust measurement with the tape snug and level, round it up to an even number and add four; 23 to 24 inches lands on 28. Letter second. Measure the bust at its fullest point and subtract the band number, and a difference of one to two inches is a B. Do both over bare skin or a thin unpadded layer, because a padded bra adds inches that the chart will faithfully convert into the wrong size.
| Inches | Centimetres | |
|---|---|---|
| Underbust | 23 to 24 | 58 to 61 |
| Bust | 29 to 30 | 74 to 76 |
| Difference | 1 to 2 | 3 to 5 |
On UK and US charts, which use the underbust itself as the band, the same body is a 24DD; EU charts call it a 50E. The bra size converter lines up all four systems.
Where do you actually buy one?
Mostly you do not, at least not labelled 28B. Indian brands tend to open their band range at 30 or 32, and 28 sits outside what they cut. The label's absence changes nothing about the measurement underneath it. That leaves two workable options, altering what exists or wearing the sister size, and 28B happens to be the one size on this band where the sister route works without an asterisk.
Sister sizes: the one that matters
Move the band up a step and the letter down a step, or the reverse, and the cup volume stays close to constant:
30A ← 28B → 26C
The right-hand option, 26C, is correct arithmetic with near-zero availability. The left-hand option is the useful one. 30A opens most stocked ranges, including ours, which makes it the doorway through which a 28B wearer reaches products that were never cut in her size. The general rule behind the pairing is in the sister sizes guide.
The standard cases:
- No 28 band to be found: buy the 30A and treat the loose band as an alteration job, not a verdict on the size.
- A 28 band you own digs in: 30A gives you the same cup with two more inches of room at the ribcage.
- Cup spills while the band sits well: the answer is 28C, which shops do not cut either; its own sister route runs through 30B.
The band's other letters, and the bust each one wraps on this same ribcage, are in the 28 bra size guide.
How does the 30A swap actually work?
A 30 band is cut for an underbust of 25 to 26 inches, about two inches more than yours, so on a hooked bra it will sit looser than the designer intended. Start on the tightest hooks rather than the loosest, so the band has somewhere left to go as the elastic relaxes with wear. If it still slides or lifts at the back, a tailor can shorten the band, and on most styles that is quick work. Check the fit every few months; a band that has relaxed past its tightest hooks is telling you to alter or replace it.
On products without a band, the swap costs nothing at all. Our strapless adhesive bra runs 30A to 40D and holds by adhesion on the skin itself. No band, no hooks, nothing to be two inches too loose: the 30A cup is moulded for the same volume a 28B carries, so you wear the sister size and give up none of the fit. What the size looks like from the other side, on someone who measures into it directly, is in 30A bra size.
Is 28B small?
It is two measurements, and only one of them is small. The band records a slim ribcage. The letter records a one to two inch difference, the same difference a 36B carries on a much wider frame. Neither number predicts the other, which is the whole reason bra sizes come in two parts. In absolute terms a 28B bust measures 29 to 30 inches around. If your own difference is under an inch, the shallower neighbour is covered in 28A bra size.
The short version
A 28B is an underbust of 23 to 24 inches with a bust of 29 to 30. Indian shops rarely cut the band, but the sister size 30A holds the same cup volume on a band two inches roomier, and it is stocked nearly everywhere; wear it on the tightest hooks or have the band taken in. On bandless products the swap is free, because there is no band to be loose. The full working for every size is in the bra size chart for India.
