Is a 40O the same in every brand?

No - a 40O isn't identical across brands, because brands use different sizing systems and cup depths. Here's how a standard US 40O translates in the brands we track: ThirdLove 40AA, Wacoal 40AA, Panache 40AA, Freya 40AA, Elomi 40AA, Glamorise 40AA, b.tempt'd 40AA, Fantasie 40AA. SHEFIT, Kindred Bravely, ENELL size by their own chart instead of band/cup.

What are the sister sizes for 40O?

40O's sister sizes — same cup volume, different band — are 42N. Try a sister size if the band feels too tight or loose but the cup still fits.

40O Bras

What is a 40O in other brands?

92 bras tracked in 40O · 2 brands · See all O cup

Brands: Elomi, Panache

Your 40O across brands

A 40O isn’t the same in every brand. Here’s how a standard US 40O translates across the brands we track — and how each one runs.

Brand	How it runs	Your 40O →
ThirdLove	cups run generous	40AA
Wacoal	true to size	40AA
Panache	true to size	40AA
Freya	band runs small	40AA

What is a 40O in other brands? See all 30+ brands →

Editorial buying guide

Read the 40O buying guide

Top picks, sister sizes, and how to spot a good 40O fit.

Read →

Sister sizes

42N What are sister sizes?

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Your 40O across brands

Kira Active Balcony Swimsuit - Mulberry

Tango Balcony Bra - Nutmeg

Tango Balcony Bra - Navy

Envy Full Cup Bra - Terracotta

Harmony Plunge Bra - Hot Pink

Bliss Full Cup Bra - Lilac

Botanical Balcony Bikini Top - Botanical Floral

Estel Full Cup Bra - Royal Blue

Estel Full Cup Bra - Sage

Josephine Full Cup Bra - Cobalt/Latte

Natalia Full Cup Bra - Bordeaux Red

Tango Balcony Bra - Chai

Envy Full Cup Bra - Chai

Envy Full Cup Bra - Chestnut

Envy Full Cup Bra - Teal

Bliss Full Cup Bra - Rose Print

Ella Plunge Bra - Black Sequin

Josephine Full Cup Bra - Forest Green

Iris Balcony Tankini Top - Green Gingham

Estel Full Cup Bra - Cherry Red

Paloma Balcony Swimsuit - Black Sand Print

Paloma Balcony Swimsuit - Navy Gingham

Dream Full Cup Bra - Navy

Tango Edit Balcony Bra - White

Anya Riva Spot Balcony Swimsuit - Navy/Vanilla

Anya Riva Balcony Swimsuit - Black

Cate Full Cup Banded Bra: White

Cate Full Cup Banded Bra: Latte

Cate Full Cup Banded Bra: Hazel

Cate Full Cup Banded Bra: Black

Cate Allure Full Cup Banded Bra: Sahara

Tango Balcony Bra - Honey

Tango Balcony Bra - Blush

Tango Balcony Bra - Black

Dream Full Cup Bra - Pistachio

Namrah Bandless Plunge Bra: Pale Blush

Lucie Stretch Plunge Bra: Wildcat

Lucie Stretch Plunge Bra: White

Lucie Stretch Plunge Bra: Pale Blush

Lucie Stretch Plunge Bra: Mocha

Lucie Stretch Plunge Bra: Mist

Lucie Stretch Plunge Bra: Black

Morgan Stretch Banded Bra: White

Morgan Stretch Banded Bra: Sahara

Morgan Stretch Banded Bra: Midnight

Morgan Stretch Banded Bra: Haute Red

Morgan Stretch Banded Bra: Black

Morgan Stretch Banded Bra: Toasted Almond

Morgan Stretch Banded Bra: Ebony

Morgan Stretch Banded Bra: Cameo Rose

Tiernie Stretch Plunge Bra: Sahara

Serene Full Cup Bra - Noir

Molly Nursing Bra: Cameo Rose

Matilda Plunge Bra: White

Matilda Plunge Bra: Sunset

Matilda Plunge Bra: Pearl Blush

Matilda Plunge Bra: Lunar Blue

Matilda Plunge Bra: Cafe Au Lait

Matilda Plunge Bra: Black

Brianna Plunge Bra: Heather