What Does Bust Size Mean?

Bust size measurements are confusing, whether you're shopping for clothing, sewing patterns, bras or formal wear. Understanding how and where to measure your bust will help you get a perfect fit, whether you're sewing clothing, ordering a sweater or investing in a custom corset. Tackle your tape measure and understand size charts with bustline basics.

Basic or Bust

If you're shopping online, most size charts include a bust measurement. Noted in inches or centimeters, this measurement is taken around the fullest part of the chest. Wearing a bra, use a cloth tape measure to measure around the largest part of your bust. Hold the tape parallel to the floor, without pulling it too tightly. This number is your full bust measurement and is essential to determine your size for tops, dresses and coats.

Under and Around

While your full bust measurement is used for clothing sizing and shopping, your underbust is used for bra or lingerie sizing. Measure under the breasts, holding the tape parallel to the floor and pulling it quite tight. If you're shopping for bras, this number is a good starting point to choose a band size. For most women, your bra band should be within an inch or two of this number.

Up and Over

Overbust measurements are taken above the fullest part of the bust, directly under the arm. These measurements are commonly used when sewing, rather than shopping. Seamstresses may choose a pattern size based on the overbust measurement and alter to fit, particularly for larger bustlines. Some women may find that the overbust measurement is helpful when choosing the correct bra size.

Bras for Your Bust

While bust size can refer specifically to measurements -- like underbust, overbust or full bust -- it can also refer to bra sizes. Bra sizes consist of both a number and a letter. The number refers to the band size, while the letter identifies the cup size. In both cases, higher numbers or letters mean a larger size. You'll need both your full bust and underbust measurements to estimate your bra size. Subtract the underbust from the full bust and use this number to determine your cup size. Allow 1 inch per cup size, from 1 inch for an A cup to 5 inches for a DD cup.