Question 1

Is a 40M the same in every brand?

Accepted Answer

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

Question 2

What are the sister sizes for 40M?

Accepted Answer

40M's sister sizes — same cup volume, different band — are 38N and 42L. Try a sister size if the band feels too tight or loose but the cup still fits.

40M Bras

Your 40M across brands

Estel Full Cup Bra - Noir

Estel Full Cup Bra - Navy

Dana Balcony Strapless Bra - Hazel

Iris Balcony Tankini Top - Red Gingham

Iris Balcony Tankini Top - Black Gingham

Selena Plunge Tankini Top - Cobalt

Paloma Balcony Swimsuit - Red Gingham

Paloma Balcony Swimsuit - Black Gingham

Rita Plunge Swimsuit - Black

Rita Plunge Swimsuit - Cobalt

Rita Plunge Swimsuit - Red

Brand	How it runs	Your 40M →
ThirdLove	cups run generous	40M
Wacoal	true to size	40M
Panache	true to size	40J
Bravissimo	true to size	40J