What cup size am I based on measurements?

Subtract your underbust from your bust measurement. Each inch of difference equals one cup size: 1 inch = A, 2 = B, 3 = C, 4 = D, 5 = DD. Combine with your band number for your full size.

Does cup volume change with band size?

Yes, as shown in our breast size chart above. A 32D has less absolute volume than a 38D. The cup letter describes the proportional difference between bust and underbust, not a fixed volume. Sister sizes preserve volume across different bands.

What is the biggest bra cup size?

Standard sizing goes up to K or beyond in both US and UK systems. Specialty brands like Elomi, Panache, and Goddess offer sizes up to UK K cup and beyond.

Reference Chart

Breast Size Chart

Updated March 2026

This breast size chart is a complete reference of every cup size from AA through K — with the bust-to-underbust difference, approximate volume, and what each size looks like in practice.

Cup Size by Difference

Your cup size is determined by the inch difference between your bust and underbust measurements. This breast size chart shows each cup letter, the difference it represents, and the approximate volume at a 34 band.

US Cup	UK Cup	EU Cup	Difference (in)	Difference (cm)	Volume (34 band)
AA	AA	AA	<1"	<2.5 cm	~65 ml
A	A	A	1"	2.5 cm	~130 ml
B	B	B	2"	5 cm	~200 ml
C	C	C	3"	7.5 cm	~275 ml
D	D	D	4"	10 cm	~360 ml
DD	DD	E	5"	12.5 cm	~450 ml
DDD / F	E	F	6"	15 cm	~550 ml
G	F	G	7"	17.5 cm	~660 ml
H	FF	H	8"	20 cm	~780 ml
I	G	I	9"	22.5 cm	~910 ml
J	GG	J	10"	25 cm	~1050 ml
K	H	K	11"	27.5 cm	~1200 ml

Volume changes with band size. The volumes above are approximate for a 34 band. A 30D has less absolute volume than a 38D, even though both are "D cups." The letter describes the proportional difference, not a fixed volume. For sizes with the same volume on a different band, see sister sizes.

Woman with measuring tape preparing to check bra size against the breast size chart

Band Size Reference

This breast size chart continues with band sizes. Your band size is your snug underbust measurement rounded to the nearest even number. Here's how underbust measurements map to band sizes across regions.

Underbust (in)	Underbust (cm)	US/UK Band	EU Band	AU Band	FR Band
26–27"	66–69 cm	28	60	6	75
28–29"	71–74 cm	30	65	8	80
30–31"	76–79 cm	32	70	10	85
32–33"	81–84 cm	34	75	12	90
34–35"	86–89 cm	36	80	14	95
36–37"	91–94 cm	38	85	16	100
38–39"	96–99 cm	40	90	18	105
40–41"	101–104 cm	42	95	20	110
42–43"	106–109 cm	44	100	22	115
44–45"	111–114 cm	46	105	24	120

Reading This Chart

Refer to this breast size chart whenever you need to look up a size. To find yours: measure your underbust (snug) and bust (fullest point). Find your underbust range in the band table to get your band number. Then subtract underbust from bust and find that difference in the cup table for your cup letter. Combine them — for example, 32 band + 3" difference = 32C. Use this breast size chart alongside our calculator for the most accurate results.

Calculator Compare Sizes Sister Sizes

For a guided walkthrough, use our bra size calculator or follow the step-by-step measuring guide. To convert between international sizing systems, try the size converter.

Bookmark this breast size chart for quick reference when shopping. To find your exact cup size, try our free bra size calculator — it takes less than a minute.