Underwire Bra Size Guide 

Not sure of your First Thing size? All you need is some quick measurements to find your perfect size. First step is to determine your ‘under bust’ size. The second step is to determine your cup size. Then use the matrix below to find your perfect size. 

 

BODY SIZE	10	12	14	16
UNDER BUST	68 - 72	73 - 77	78 - 82	83 - 87
Cup A	82-84	87-89	92-94	97-99
Cup B	84-86	89-91	94-96	99-101
Cup C	86-88	91-93	96-98	101-103
Cup D	88-90	93-95	98-100	103-105
Cup DD	90-92	95-97	100-102	105-107
Cup E	92-94	97-99	102-104	107-109

 

Soft Bra Size Guide

SIZE	XS	S	M	L
CLOTHING SIZE	8	10	12	14
UNDER BUST	68 - 67	68-72	73-77	78-82

Bottoms Size Guide

SIZE	XS	S	M	L	XL
CLOTHING SIZE	8	10	12	14	16
HIP MEASUREMENT (CM)	87-92	92-97	97-102	102-107	107-112

Sister Sizing  

Did you know that if you fit into one bra size, chances are you’ll fit into several other sizes too? Bra size doesn’t work the same way as clothing sizes as the band size varies with the size of the cup like a ratio.

If you go up a band size, you’ll go down a cup size and similarly, if you go down a band size, you’ll go up a cup size.

Here’s a simple chart to show your sister size – use the colours and numbers to help match the sizes. For example if you’re a 12D, you could also fit a 10DD (down a band size and up a cup size) or 14C (up a band size and down a cup size)

8	10	12	14	16	18	EXAMPLE
A	A	A	A	A	A
A	B	B	A	B	B	A 14D is equivalent to 16C and 12DD
C	C	C	C	C	C	A 12E is equivalent to 10F and 14DD
D	D	D	D	D	D	A 12E is equivalent to 10F and 14DD
DD	DD	DD	DD	DD	DD	An 18DD is equivalent to 16E and 20D
E	E	E	E	E	E	A 12E is equivalent to 10F and 14DD
F	F	F	F	F	F	A 12E is equivalent to 10F and 14DD
G	G	G	G	G	G