A woman compares two sister sizes to her correctly-fitting bra (right).[1]
Sister sizes always have the same cup volume as each other.[2]
A sister size is a related bra size with the same cup volume of each other. One's sister size could, in theory, be used as a substitute for one's true size, but the bra wouldn't fit correctly.[3]
Theory
This illustration compares breast volumes. Listed volumes are volume per breast.[4]
Sister sizes have the same cup volume as each other. The difference of band size simply changes the fit.
Typical stores suggest sister sizes to sell their limited inventory to the customer, as opposed to a bra that actually fits. This perpetuates the problem of most women wearing band sizes too large, with correspondingly wrong cup sizes.[3]
Sometimes, two adjacent sister sizes may both fit a woman, since the cup volume is the same, while the band size can be adjusted to a small degree by using the hook and eye fasteners in the bra clasp.[3] However, it is usually less comfortable and flattering.
Charts
- Main article: Bra sizing by country
UK sister sizes
| 26 | 28 | 30 | 32 | 34 | 36 | 38 | 40 | 42 | 44 | 46 | 48 | 50 | 52 | 54 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 26AA | ||||||||||||||
| 26A | 28AA | |||||||||||||
| 26B | 28A | 30AA | ||||||||||||
| 26C | 28B | 30A | 32AA | |||||||||||
| 26D | 28C | 30B | 32A | 34AA | ||||||||||
| 26DD | 28D | 30C | 32B | 34A | 36AA | |||||||||
| 26E | 28DD | 30D | 32C | 34B | 36A | 38AA | ||||||||
| 26F | 28E | 30DD | 32D | 34C | 36B | 38A | 40AA | |||||||
| 26FF | 28F | 30E | 32DD | 34D | 36C | 38B | 40A | 42AA | ||||||
| 26G | 28FF | 30F | 32E | 34DD | 36D | 38C | 40B | 42A | 44AA | |||||
| 26GG | 28G | 30FF | 32F | 34E | 36DD | 38D | 40C | 42B | 44A | 46AA | ||||
| 26H | 28GG | 30G | 32FF | 34F | 36E | 38DD | 40D | 42C | 44B | 46A | 48AA | |||
| 26HH | 28H | 30GG | 32G | 34FF | 36F | 38E | 40DD | 42D | 44C | 46B | 48A | 50AA | ||
| 26J | 28HH | 30H | 32GG | 34G | 36FF | 38F | 40E | 42DD | 44D | 46C | 48B | 50A | 52AA | |
| 26JJ | 28J | 30HH | 32H | 34GG | 36G | 38FF | 40F | 42E | 44DD | 46D | 48C | 50B | 52A | 54AA |
| 26K | 28JJ | 30J | 32HH | 34H | 36GG | 38G | 40FF | 42F | 44E | 46DD | 48D | 50C | 52B | 54A |
| 26KK | 28K | 30JJ | 32J | 34HH | 36H | 38GG | 40G | 42FF | 44F | 46E | 48DD | 50D | 52C | 54B |
| 26L | 28KK | 30K | 32JJ | 34J | 36HH | 38H | 40GG | 42G | 44FF | 46F | 48E | 50DD | 52D | 54C |
| 26LL | 28L | 30KK | 32K | 34JJ | 36J | 38HH | 40H | 42GG | 44G | 46FF | 48F | 50E | 52DD | 54D |
| 26M | 28LL | 30L | 32KK | 34K | 36JJ | 38J | 40HH | 42H | 44GG | 46G | 48FF | 50F | 52E | 54DD |
| 26MM | 28M | 30LL | 32L | 34KK | 36K | 38JJ | 40J | 42HH | 44H | 46GG | 48G | 50FF | 52F | 54E |
| 26N | 28MM | 30M | 32LL | 34L | 36KK | 38K | 40JJ | 42J | 44HH | 46H | 48GG | 50G | 52FF | 54F |
| 28N | 30MM | 32M | 34LL | 36L | 38KK | 40K | 42JJ | 44J | 46HH | 48H | 50GG | 52G | 54FF | |
| 30N | 32MM | 34M | 36LL | 38L | 40KK | 42K | 44JJ | 46J | 48HH | 50H | 52GG | 54G | ||
| 32N | 34MM | 36M | 38LL | 40L | 42KK | 44K | 46JJ | 48J | 50HH | 52H | 54GG | |||
| 34N | 36MM | 38M | 40LL | 42L | 44KK | 46K | 48JJ | 50J | 52HH | 54H | ||||
| 36N | 38MM | 40M | 42LL | 44L | 46KK | 48K | 50JJ | 52J | 54HH | |||||
| 38N | 40MM | 42M | 44LL | 46L | 48KK | 50K | 52JJ | 54J | ||||||
| 40N | 42MM | 44M | 46LL | 48L | 50KK | 52K | 54JJ | |||||||
| 42N | 44MM | 46M | 48LL | 50L | 52KK | 54K | ||||||||
| 44N | 46MM | 48M | 50LL | 52L | 54KK | |||||||||
| 46N | 48MM | 50M | 52LL | 54L | ||||||||||
| 48N | 50MM | 52M | 54LL | |||||||||||
| 50N | 52MM | 54M | ||||||||||||
| 52N | 54MM | |||||||||||||
| 54N |
US sister sizes
| 28 | 30 | 32 | 34 | 36 | 38 | 40 | 42 | 44 | 46 | 48 | 50 | 52 | 54 | 56 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 28AA | ||||||||||||||
| 28A | 30AA | |||||||||||||
| 28B | 30A | 32AA | ||||||||||||
| 28C | 30B | 32A | 34AA | |||||||||||
| 28D | 30C | 32B | 34A | 36AA | ||||||||||
| 28DD/E | 30D | 32C | 34B | 36A | 37AA | |||||||||
| 28DDD/F | 30DD/E | 32D | 34C | 36B | 38A | 40AA | ||||||||
| 28DDDD/G | 30DDD/F | 32DD/E | 34D | 36C | 38B | 40A | 42AA | |||||||
| 28H | 30DDDD/G | 32DDD/F | 34DD/E | 36D | 38C | 40B | 42A | 44AA | ||||||
| 28I | 30H | 32DDDD/G | 34DDD/F | 36DD/E | 38D | 40C | 42B | 44A | 46AA | |||||
| 28J | 30I | 32H | 34DDDD/G | 36DDD/F | 38DD/E | 40D | 42C | 44B | 46A | 48AA | ||||
| 28K | 30J | 32I | 34H | 36DDDD/G | 38DDD/F | 40DD/E | 42D | 44C | 46B | 48A | 50AA | |||
| 28L | 30K | 32J | 34I | 36H | 38DDDD/G | 40DDD/F | 42DD/E | 44D | 46C | 48B | 50A | 52AA | ||
| 28M | 30L | 32K | 34J | 36I | 38H | 40DDDD/G | 42DDD/F | 44DD/E | 46D | 48C | 50B | 52A | 54AA | |
| 28N | 30M | 32L | 34K | 36J | 38I | 40H | 42DDDD/G | 44DDD/F | 46DD/E | 48D | 50C | 52B | 54A | 56AA |
| 30N | 32M | 34L | 36K | 38J | 40I | 42H | 44DDDD/G | 46DDD/F | 48DD/E | 50D | 52C | 54B | 56A | |
| 32N | 34M | 36L | 38K | 40J | 42I | 44H | 46DDDD/G | 48DDD/F | 50DD/E | 52D | 54C | 56B | ||
| 34N | 36M | 38L | 40K | 42J | 44I | 46H | 48DDDD/G | 50DDD/F | 52DD/E | 54D | 56C | |||
| 36N | 38M | 40L | 42K | 44J | 46I | 48H | 50DDDD/G | 52DDD/F | 54DD/E | 56D | ||||
| 38N | 40M | 42L | 44K | 46J | 48I | 50H | 52DDDD/G | 54DDD/F | 56DD/E | |||||
| 40N | 42M | 44L | 46K | 48J | 50I | 52H | 54DDDD/G | 56DDD/F | ||||||
| 42N | 44M | 46L | 48K | 50J | 52I | 54H | 56DDDD/G | |||||||
| 44N | 46M | 48L | 50K | 52J | 54I | 56H | ||||||||
| 46N | 48M | 50L | 52K | 54J | 56I | |||||||||
| 48N | 50M | 52L | 54K | 56J | ||||||||||
| 50N | 52M | 54L | 56K | |||||||||||
| 52N | 54M | 56L | ||||||||||||
| 54N | 56M | |||||||||||||
| 56N |
