BraSizeConversion

38B Bra Size, Fully Explained

7 sizing systems25+ country calculatorsBands 28-60, cups AA-PZero data stored

38B is squarely in the core of the size chart: a mid-range band with a gentle difference. Nearly every brand cuts it, which makes fit problems here almost always construction or wear-routine issues rather than availability ones.

38B in every sizing system

USUKEUFRAUJPKR
38B38B85B100B16BC85C85

Sister sizes of 38B

34D36C38B40A42AA

Each sister holds roughly the volume of 38B on a different band. Band riding up in a 38B? Try 36C. Band digging painfully? The other direction.

How 38B compares, visually

38A38B38C

Circle areas scale with estimated cup volume: 38B206 cc per cup, roughly 0.2 kg of tissue per side at typical density. Model documented on the weight page.

Is 38B big?

Is 38B big? In absolute terms it is on the smaller side of the chart, but the honest answer is that the question is mostly noise: the letter only means something relative to the 38 band, and bodies wear the same volume completely differently. What matters is that 38B fits its wearer, which the fit checks decide better than comparison ever will.

Shopping notes for 38B

Confirm the size first: two minutes with the calculator beats inheriting a label. Then let the brand decoder translate 38B into each brand's cut, since the same tag runs shallow at mall brands and deep at UK houses. If 38B passes the band checks but the cup misbehaves, that is usually shape, not size.

Frequently asked questions

What is 38B in UK and European sizing?
38B (US) converts to UK 38B, EU 85B, FR 100B, AU 16B and JP/KR C85. Cup letters diverge after D, which is why the letters differ between systems.
What are the sister sizes of 38B?
34D, 36C, 40A, 42AA. Each holds approximately the same cup volume as 38B on a different band: band down pairs with letter up, and vice versa.
Is 38B big?
What matters is that 38B fits its wearer, which the fit checks decide better than comparison ever will..
How much do 38B breasts weigh?
Roughly 0.2 kg (0.4 lb) per breast as an estimate from cup volume at typical tissue density. Real weight varies with tissue composition; see our breast weight page for the method.
Nearby sizes

Last updated August 2026.