I often wear anywhere from a 38 ddd to a 40f in department store brands and this 40f fits very snug in the band on the loosest setting which is why i rated it somewhat small

I just used the size chart to estimate my size 40 f didnt even measure with a tape so i was anticipating that i might need to return for a different size but luckily it fit perfectly

I can even wear it under some tshirts