A 30B is the narrowest band most Indian brands make, paired with a low cup letter. If it is your size, the useful thing to understand is what happens at the edge of a stocked range, because that is where the fitting advice stops working as written.
Our bra size calculator gives you the band, the letter and the sizes either side in one step.
What a 30B measures
Indian band sizing is your underbust rounded up to an even number plus four inches. A 30 band is cut for an underbust of about 25 to 26 inches.
The letter is the difference between bust and band. B is one to two inches.
| Inches | Centimetres | |
|---|---|---|
| Underbust | 25 to 26 | 64 to 66 |
| Bust | 31 to 32 | 79 to 81 |
| 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 26DD; EU charts call it a 55E. The bra size converter lines up all four systems.
What 30B means in practice
The number is not your ribcage measurement, which is the single most common misreading of an Indian size. A 30 band suits someone measuring 25 or 26 inches underneath, because the convention adds four inches to that measurement before printing the label.
The letter is not a volume either. It records how much bigger your bust is than your band. A B on a 30 band is a genuinely small cup, and a B on a 38 is not, even though both say B.
What if your underbust is under 25 inches?
Then the arithmetic gives you a 28 band, and most Indian brands do not make one. This is a stock problem rather than a sizing problem, and it has two workable answers.
The first is to take the 30 and use the hooks. A 30 on the tightest hook is the closest thing on the rail, and a band with some adjustment left in it beats one already at its limit. Look for a wider back panel too, since it spreads the pressure and holds better at a small band.
The second is to pick a style with no band at all. For anything fitted or strapless, an adhesive bra removes the question entirely, because there is no band to be the wrong size.
What does not work is going up to a 32 for comfort. A band two inches too wide will ride up your back all day, and the straps will end up carrying what the band should.
Is 30B or 32A bigger?
They hold a similar amount. They are sister sizes, and the difference is which band you need rather than which cup.
A 30B is a one to two inch difference on a 30 band, so a bust of 31 to 32 inches. A 32A is a zero to one inch difference on a 32 band, so a bust of 32 to 33. The cups are close. The bands are two inches apart, and that is the part your body decides.
Since 32 is stocked far more widely than 30, plenty of people who measure 30B are wearing a 32A. If yours stays put and feels level all day, it is fine. If it rides up, the 30B was the right answer.
Is 30B or 32B bigger?
32B, in both dimensions. It is a wider band, and because a letter is measured against its own band, the B on a 32 is a larger cup than the B on a 30.
That combination is the trap when a 30 is unavailable. Taking the 32B gives you a looser band and a larger cup, so nothing about it is closer to your measurements. The sister size, 32A, at least keeps the cup right.
Sister sizes when 30B is close but wrong
Move the band one step and the letter the opposite way:
32A ← 30B → 28C
- Band rides up at the back, cup fits: go down to 28C, if you can find one
- Band comfortable, spilling over the top: stay on 30 and go up to 30C
- Band digs in, cup fits: go up to 32A
The 28C half of that pair is usually not buyable in India, so 30C on the tightest hook is the practical version of the same move.
When the outfit leaves nowhere for a band
Backless blouses, halter necks, deep V necklines and low saree drapes take the band away, and at a narrow band that is sometimes a relief rather than a problem.
- A strapless adhesive bra in your cup size sticks to skin and holds shape with no band at all. It is made in 30B, the smallest band in the range.
- Nipple covers where you want coverage under a thin fabric and nothing more.
- Lift tape for a specific neckline, placed where you want the lift.
Adhesive styles have less weight to hold at this size, so they tend to stay put longer and feel lighter than they do further up the range.
The short version
A 30B fits an underbust of 25 to 26 inches with a bust an inch or two larger. It is the narrowest band on most Indian rails, so if your measurement points below it, use the tightest hook rather than sizing up, and consider a style with no band at all. Between 30B and 32A, your ribcage decides.
The full method is in our bra size chart for India, and the next letter up on a narrow band is covered in 32B bra size. The 30 bra size guide puts the band's four cups on one page.
