38B vs 38C
One cup letter apart on the same band. Here is what one inch of difference actually changes, and how to know which is yours.
38B or 38C, in short
38B and 38C share the 38 band; 38C holds one cup step more volume: about one inch of bust. You are 38C if 38B spills, floats at the gore or puts the wire on tissue; you are 38B if 38C gapes or wrinkles at the top. If the band is wrong in either, that is a sister-size change, not a cup change.
38B and 38C, side by side
Same band bar, bigger dome: one inch more bust on the same frame: the cup grows, the band does not.
38B or 38C?
- 38B cups spill over the top or at the sides
- The gore floats off the sternum in a 38B
- The wire sits on breast tissue in a 38B
- 38C cups gape or wrinkle at the top
- 38C molded cups leave a hollow at the apex
- 38B fills evenly with a smooth top edge
Both share the 38 band. If the band is wrong in either, that is a separate fix (sister sizes (36C / 40A)) not a cup change.
Brands that carry both 38B and 38C
Range-checked against each brand's core collections, with both sizes written in the brand's own notation.
| Brand | 38B as | 38C as | System | How it runs |
|---|---|---|---|---|
| Wacoal | 38B | 38C | US | Band true to size · cups true |
| Natori | 38B | 38C | US | Band soft / stretchy · cups grades small |
| Le Mystère | 38B | 38C | US | Band firm · cups true |
| Victoria's Secret | 38B | 38C | US | Band soft / stretchy · cups grades small |
| Maidenform | 38B | 38C | US | Band true to size · cups true |
| Bali | 38B | 38C | US | Band true to size · cups grades generous |
| Playtex | 38B | 38C | US | Band true to size · cups grades generous |
| Warner's | 38B | 38C | US | Band true to size · cups true |
| Soma | 38B | 38C | US | Band true to size · cups true |
| ThirdLove | 38B | 38C | US | Band true to size · cups grades generous |
Every brand page converts your measured size and notes how it runs. All bra brands →
38B and 38C in every system
| US | UK | EU / DE / JP | FR / ES | AU / NZ | IT |
|---|---|---|---|---|---|
| 38B | 38B | 85B | 100B | 16B | 5B |
| 38C | 38C | 85C | 100C | 16C | 5C |
The one-cup step is one letter in every alphabet, but above D the letters diverge (US DDD = UK E = EU F).
The five fit checks, 38B vs 38C
| Check | What right looks like | What it tells you here |
|---|---|---|
| Band | Level, snug on the loosest hook, two fingers underneath, no ride-up | Identical band in both: if it fails, change the band with a sister size, not the cup |
| Cups | Filled to the top edge with no gap and no spill | 38C fills where 38B spills; 38B fills where 38C gapes |
| Gore | Flat against the sternum | A floating gore in 38B points to 38C |
| Straps | Light duty, no digging | Unrelated to the cup step; a strap problem is a band problem |
| Wire | On the ribcage, not on tissue | Wire on tissue in 38B points to 38C |
What goes wrong choosing between 38B and 38C
| Mistake | Why it fails |
|---|---|
| Going up a band instead of a cup when 38B spills | A bigger band with the same letter is a bigger cup AND a looser band; 38C keeps the band and adds only volume |
| Sizing down to 38B for a 'lifted' look | Spillage isn't lift; it is a cup too small |
| Judging by a molded cup only | Molded cups exaggerate both gap and spill; check a seamed cup before deciding |
Availability, shape and the +4 check
Related comparisons
38B vs 38C: answered
What is the difference between 38B and 38C?
One inch of bust on the same 38″ band: 38B is a 2″ difference, 38C a 3″ difference. 38C holds one cup step more volume; the band is identical.
Is 38B bigger than 38C?
38C is bigger by one cup step (about an inch of bust). Same band.
Can I wear 38C instead of 38B?
Only if the 38B cups are actually too small: spillage, floating gore or wire on tissue. Going up a cup for a band problem makes both worse.
What are 38B and 38C in UK and EU sizing?
38B: UK 38B, EU 85B, FR 100B. 38C: UK 38C, EU 85C, FR 100C.
Do 38B and 38C fit the same in every brand?
The relationship holds everywhere; the fit doesn't. Brands with soft bands push you toward the snugger sister, firm bands toward the looser; brands whose cups grade small push you up a cup. The brand table above shows how each runs.
Which is more common, 38B or 38C?
38B is one of the most widely stocked sizes; 38C is one of the most widely stocked sizes.
Should I own both 38B and 38C?
Usually one is right and the other is a mistake in the cup, but shape-dependent: a molded style may fit in one and a seamed style in the other.
How do I measure to tell 38B from 38C?
Underbust snug (36.5–38.4″ gives band 38), bust at the fullest point; the difference sets the cup. Then confirm on the body with the five fit checks.
HauteFlair labels cups in UK letters, so these links already convert your size by position (a US DDD lands on a UK E, a US G on a UK F). HauteFlair is owned by the same company as Brasize.ai; that relationship never changes the sizing math, charts, or fit advice on this page. How this site makes money.
Not sure which you are?
Two measurements settle it, then read the guide for your size.
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