We asked experts how to measure your bra size correctly so that you can find one that fits perfectly. Below, experts explain the signs that your bra doesn’t fit, how to properly measure yourself for a new bra, and tips to help your bra stay supportive for longer. How to find your bra size with a measuring tapeYou should be measuring your bra size yearly to ensure full comfort in your underpinnings. Here's how:Step 1: Find your bra band sizeWearing an unlined, non-padded bra (not over your clothes!) "A sister size refers to a bra size that has the same cup capacity with a different band size," says Seymour.