Size conversion
What Is a 40O in Other Brands?
Bra sizes are not standardized: the same label means different things brand to brand, so your 40O is a starting point, not a fixed size. A US 40O usually needs a 40AA in Victoria’s Secret, maps to a 40AA in a true-to-size UK brand like Panache, and stays a 40AA in Wacoal.
Your 40O in Victoria's Secret
40AA
Cups run a full cup small, so size up
Your 40O in Panache
40AA
True-to-size UK sizing
Your 40O in Wacoal
40AA
True to size, year after year
Every brand we track
Your 40O, brand by brand
Grouped by the sizing system each brand labels its cups in. Brands we stock link to their full lineup.
US
US-sized brands
| Brand | How it runs | Your 40O → |
|---|---|---|
| ThirdLovein stock | cups run generous | 40AA |
| Wacoalin stock | true to size | 40AA |
| Glamorisein stock | true to size | 40AA |
| SHEFITin stock | - | Adjustable XS-6Luxe sizing rather than standard band/cup; size by the brand chart. |
| b.tempt'din stock | true to size | 40AA |
| Kindred Bravelyin stock | - | Uses XS-XXL nursing/maternity sizing rather than band/cup; size by the brand chart. |
| ENELLin stock | - | Uses numeric high-impact sizing (00-8) rather than band/cup; size by the brand chart. |
| Natori | cups run small | 40AA |
| Bali | band runs large | 38AA |
| Playtex | band runs large | 38AA |
| Maidenform | true to size | 40AA |
| Vanity Fair | band runs large | 40AA |
| Calvin Klein | band runs small | 40AA |
| Victoria's Secret | cups run small | 40AA |
| Brooks | band runs small | 40AA |
| Under Armour | - | Compression fit runs generous; XS-XL sizing rather than band/cup; size by the brand chart. |
| Nike | - | Generous fit; XS-XL sizing rather than band/cup; size by the brand chart. |
| Cacique | band runs large | 40AA |
| Torrid | band runs large | 40AA |
UK
UK-sized brands (cups run D, DD, E, F, FF, G...)
EU
EU-sized brands
| Brand | How it runs | Your 40O → |
|---|---|---|
| Chantelle | cups run small | 40AA |
| Simone Perele | cups run small | 40AA |
| PrimaDonna | true to size | 40AA |
| Marie Jo | true to size | 40AA |
| Triumph | band runs large | 40AA |
| Anita | true to size | 40AA |
Translations are guidance from cross-brand fit data, not a guarantee - fit also depends on breast shape and style. Cross-brand offset data v1-2026-05-28.
In stock now
Shop 40O now
Real bras we track in stock in 40O, with live prices.
Elomi
Molly Nursing Bra: Cameo Rose
$75.00View →
Elomi
Matilda Plunge Bra: White
$75.00View →
Elomi
Matilda Plunge Bra: Sunset
$75.00View →
Elomi
Matilda Plunge Bra: Pearl Blush
$75.00View →
Elomi
Matilda Plunge Bra: Lunar Blue
$75.00View →
Elomi
Matilda Plunge Bra: Cafe Au Lait
$75.00View →
Elomi
Matilda Plunge Bra: Black
$75.00View →
Elomi
Brianna Plunge Bra: Heather
$75.00View →
40O sister sizes
Sister sizes hold the same cup volume on a different band. If the 40O cup fits but the band doesn’t, try:
Interactive
Try your own size
Not a 40O? Enter any size to see it in every brand. Your size never leaves your browser.
Brand Size Translator
Find your size across different brands
40O
Why sizes vary: Each brand uses different patterns, materials, and fit philosophies. A 34DD in Victoria's Secret fits differently than a 34DD in Panache.
ThirdLove
US
Half-cup sizing available; cups run slightly generous.
40AA
Wacoal
US
True to size; consistent fit across decades.
40AA
Panache
UK
UK sizing; true to size, consistent year over year.
40AA
Freya
UK
UK sizing; bands run snug.
40AA
Elomi
UK
UK plus-size full-bust; cups run generous.
40AA
Glamorise
US
US full-figure; true to size.
40AA
SHEFIT
US
Adjustable XS-6Luxe sizing rather than standard band/cup; size by the brand chart.
40AA
b.tempt'd
US
Wacoal-family fit DNA; runs true to US sizing, lighter construction.
40AA
Kindred Bravely
US
Uses XS-XXL nursing/maternity sizing rather than band/cup; size by the brand chart.
40AA
ENELL
US
Uses numeric high-impact sizing (00-8) rather than band/cup; size by the brand chart.
40AA
Natori
US
Cups run small; consider sizing up.
40AA
Chantelle
EU
French sizing; cups run small.
40AA
Bali
US
Bands run loose; consider sizing down.
38AA
Playtex
US
Bands run large; size down in band.
38AA
Maidenform
US
Generally true to size.
40AA
Vanity Fair
US
Bands run slightly loose.
40AA
Calvin Klein
US
Bands run slightly snug.
40AA
Victoria's Secret
US
Cups run very small; size up a full cup.
40AA
Fantasie
UK
UK sizing; consistent fit.
40AA
Curvy Kate
UK
UK sizing; bands run firm.
40AA
Gossard
UK
UK sizing; classic fit.
40AA
Pour Moi
UK
UK sizing; budget-friendly.
40AA
Simone Perele
EU
French luxury; cups run small.
40AA
PrimaDonna
EU
Belgian luxury; true EU sizing.
40AA
Marie Jo
EU
Belgian; consistent fit.
40AA
Triumph
EU
German; bands slightly generous.
40AA
Anita
EU
German; strong post-surgery range.
40AA
Brooks
US
Compression sports style; may run snug.
40AA
Under Armour
US
Compression fit runs generous; XS-XL sizing rather than band/cup; size by the brand chart.
40AA
Nike
US
Generous fit; XS-XL sizing rather than band/cup; size by the brand chart.
40AA
Goddess
UK
UK sizing; strong plus-size range.
40AA
Cacique
US
Lane Bryant's brand; bands run generous.
40AA
Torrid
US
Plus-focused; bands run large.
40AA
Common questions
40O conversion questions
- What is a 40O in Victoria's Secret?
- Victoria's Secret cups run about a full cup small, so a standard US 40O usually needs a 40AA there. If you already wear a 40O in Victoria's Secret, your size in a true-to-size brand is likely a cup smaller.
- Which brands keep a 40O the same?
- In true-to-size brands a US 40O stays a 40O: Wacoal, Panache, Glamorise, b.tempt'd, Maidenform, Fantasie, Gossard, Pour Moi, PrimaDonna, Marie Jo, Anita, Goddess. Fit can still vary by style, so treat the label as the starting point.
- Do UK brands size a 40O differently from US brands?
- UK brands label cups in a different sequence above D (D, DD, E, F, FF, G), so the same letters can mean different volumes. In a true-to-size UK brand like Panache, a US 40O is a 40AA; the band number stays the same.
- What size replaces a 40O in brands that don't use cup sizes?
- SHEFIT, Kindred Bravely, ENELL, Under Armour, Nike size by their own charts (XS-XL or numeric) instead of band/cup, so a 40O doesn't carry over directly. Start from each brand's chart with your underbust and bust measurements.