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40C bra size — conversions, sister sizes & fit
A 40C fits an underbust of about 87.5–92.5 cm with a bust 13.75–16.25 cm larger than the band. Here is everything that label actually means — and how to check it really fits you.
Your bra size
40C US
Which measurements give 40C?
| cm | |
|---|---|
| Underbust (snug) | 87.5–92.5 |
| Bust (fullest point) | 101.25–108.75 |
| Difference (cup volume) | 13.75–16.25 |
Between two sizes? Measurements near the edges of these ranges can also fit the neighbouring size — check the sister sizes below and, in doubt, trust the fit checks from our measuring guide.
Sister sizes of 40C
38D and 42B hold a similar cup volume to 40C with a tighter or looser band. If the band of a 40C rides up, try 38D; if it digs in, try 42B.
In the middle of the cup range, brands' cuts differ noticeably: the same label can run a full cup apart between two houses. Lean on the fit checks — band level, wire flat against the sternum, no spill, no gap — rather than the label, and keep both sister sizes in mind at the fitting room.
40C in the Cherry Size catalogue In the Cherry Size catalogue, 357 of 617 brands have a recorded size range that includes 40C. That count uses each brand's band range and largest cup (the smallest cup is not recorded) and includes ranges not yet checked. Each of them cuts it differently: the app estimates the size to try at each brand, from your own measurements.In the app, your size is free, and so is your size at 3 brands you choose. Every brand, the fitting room, the wardrobe and the journal need a subscription, with a free trial for eligible new subscribers.
See 40C brand by brand40C in questions
What is 40C in European sizing?
A 40C corresponds to 90C in European sizing and 105C in French/Spanish sizing, by the usual correspondences. The conversion changes the band numbering, and from DD up the cup letter too (US DD = EU E); individual brands can differ.
Is 40C big or small?
It sits in the middle of the cup range, between smaller and fuller cups. Cup letters mean nothing alone: a cup only has a volume relative to its band, which is why 38D and 42B hold a similar volume to 40C.
My 40C doesn't fit — what should I try?
If the band rides up or feels loose, go to 38D. If the band digs in while the cup is fine, go to 42B. If the cup overflows, try one cup up in the same band; if it wrinkles empty, one cup down. Two minutes with the calculator gives you a fresh estimate.
Nearby sizes
Your size, everywhere you shop
Cherry Size keeps your measurements on your iPhone, translates them into 617 brands, tracks changes through pregnancy, nursing or weight shifts (with a subscription) — and never uploads a thing. In the app, your size is free, and so is your size at 3 brands you choose. Every brand, the fitting room, the wardrobe and the journal need a subscription, with a free trial for eligible new subscribers.
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