What is A Cup Size? A Cup Bra Measurements in Inches & cm, 30A to 40A

In bra sizing, an A cup means your bust measures about 1 inch (2.5 cm) more than your band size. So "A cup" is not one fixed size: a 32A has a bust of about 33 inches and a 38A a bust of about 39 inches, because the cup letter only describes the difference between bust and band. A is the smallest standard cup. Below is every A cup size from 30A to 40A with its measurements in inches and cm, how to check you are an A cup, which sizes hold the same cup volume, and which bra styles suit an A cup.

A cup size chart: 30A to 40A

Size	Underbust (inches)	Bust (inches)	Bust (cm)	Shop
30A	25–26	31	79	30 bras
32A	27–28	33	84	32 bras
34A	29–30	35	89	34 bras
36A	31–32	37	94	36 bras
38A	33–34	39	99	38 bras
40A	35–36	41	104	40 bras

Every row is an A cup, but the cups are not the same size: cup volume grows with the band, so a 38A cup holds noticeably more than a 32A cup. The band number is your underbust plus 4 (even) or 5 (odd) inches; the cup letter is bust minus band, where A is 1 inch, B is 2, C is 3, D is 4 and E is 5.

How to know if you are an A cup

Measure under your bust, snug, in inches, and convert to a band: add 4 if the number is even, 5 if it is odd.
Measure around the fullest part of your bust, loosely, without pressing.
Subtract the band from the bust. A difference of 1 inch is an A cup; 2 is B.

Example: underbust 29 inches gives band 34; bust 35 inches is 35 minus 34 = 1, so 34A. Use the bra size chart for every band or the bra size calculator to do the maths.

Is A cup big or small?

On Lovable India, A cups are bought mostly by teenagers, slim frames and petite women; 32A and 34A are the most-bought A sizes. On its own, the letter says little about how a bust looks: an A cup on a 30 band is small, an A cup on a 40 band is full. A is the smallest standard cup; B is one inch larger.

A cup sister sizes

Sister sizes share the same cup volume on a different band. If your A cup bra fits in the cup but the band is tight, go up a band and down a cup; if the band rides up, go down a band and up a cup.

A cup size	Same cup, tighter band	Same cup, looser band
30A	–	–
32A	30B	–
34A	32B	–
36A	34B	–
38A	36B	–
40A	38B	–

Best bra styles for A cups

A cups need shape more than support. Padded and push-up bras add a cup size of lift under fitted tops and blouses; t-shirt bras with moulded cups give a smooth, rounded line; lightly padded non-wired bras are comfortable for all day; demi and balconette cuts suit A cups well because there is nothing to spill. Non-padded cotton bras work for home and sleep, but most A-cup customers buy padded. Browse t-shirt bras, padded bras, non-padded bras, seamless bras, sports bras and full coverage bras, then filter to your A cup size.

A cup FAQs

What does A cup mean?

That your bust is about 1 inch (2.5 cm) larger than your band size. It is a difference, not a measurement, so the actual cup size depends on the band: 32A, 34A and 36A are all A cups of different sizes.

What is A cup size in cm?

The difference between bust and band is about 2.5 cm. In centimetres the full sizes are: 32A bust 84 cm, 34A bust 89 cm, 36A bust 94 cm, 38A bust 99 cm.

What is the difference between A cup and B cup?

One inch. An A cup is a bust 1 inch larger than the band; a B cup is 2 inches larger. On a 34 band that is a bust of 35 inches (34A) versus 36 inches (34B).

Which A cup size is most common in India?

32A and 34A, mostly for teenagers and petite women.

Is an A cup the same on every band?

No. Cup volume increases with the band, so 36A holds more than 34A, which holds more than 32A. The size with the same cup volume as 34A is 32B on a tighter band; on a 36 band it would be a 36AA, which few Indian brands stock, so most 34A customers who need a looser band simply move to 36A.

Which bra is best for an A cup?

A padded or push-up t-shirt bra for shape under fitted clothes, and a lightly padded non-wired bra for daily wear. See all bras on Lovable India from ₹179 and filter to your A cup size.

More bra size guides

Bra Size Chart | Bra Size Calculator | What A, B, C, D Cup Sizes Mean

By band: 30 Bra Size | 32 Bra Size | 34 Bra Size | 36 Bra Size | 38 Bra Size

By size: 30B | 32B | 32C | 32D | 34B | 34C | 34D | 36B | 36C | 36D | 38B | 38C | 38D

By cup: B Cup | C Cup | D Cup

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