Eighty-five percent of women are wearing the wrong size, according to a survey of 500 customers conducted by Intimacy lingerie stores. If it’s been a while since you were professionally fitted, chances are you, too, are wearing the wrong size.

Keep in mind that your size can change if you:

Gain or lose weight.

Start or stop exercising.

Become pregnant.

Start or stop nursing.

Use birth-control pills or hormone-replacement therapy.

Alter your diet.

Another factor to consider is the difference between American and European sizing conventions. European bra makers don’t recognize double-letter cup sizes. So for them a 34DD is equal to a 32E.

Tip: Normal wear and tear, body heat, and sweat can break down spandex, as can overwashing. Ideally, hand wash a bra after every two uses.