"I tell people all the time, 'You only think you’re comfortable. You’re not comfortable. You have no idea what comfort is. Wait until I get you in a bra that fits.' When you wear a bra that fits, it’s like, 'Oh my God, I can’t believe it.'" Yup, she's that serious about bras.

When we waltzed in and told her we'd been told we were a 34C, she asked if the person who said that had been drunk at the time. She whipped out a tape measurer, did some magic, and sent us home with a 30E. (We're still trying to wrap our heads around that one).

After a 25-year career and two Manhattan stores (plus online), Linda says most women are sorely in the dark about what size they actually are. We asked her about how to know whether you're in the right size, bra life and care, and more.

Real Beauty: So how do you know if a bra's not fitting your properly?

Linda Becker: You know it doesn't fit right if it rides up in the back—that means the band's too big. People think there's something wrong with the straps if they're falling off the shoulders all the time, but what that really means is that the band's too big. If your bra moves constantly and you're always adjusting it, it doesn't fit.

RB: When trying on bras, what's the most important thing to look for?

LB: Your band has to be snug! When it fits right, the bra should be on the loosest hook, and it should be snug because as it gets older, you'll want to be able to tighten it up. I can’t say it enough—your bra should never be loose. It needs to be snug, and I mean snug. Not tight, but snug.

RB: Like snug enough to leave marks on your skin?