Shopping for a training bra can be a memorable and exciting time in a young woman's life. A well-fitting and comfortable bra is very important during the teen years. Measure carefully to ensure the best possible fit.

Measure frame size. Using the tape measure, measure the diameter around the chest, directly below the breasts, in inches. Record this measurement to the nearest inch on paper.

Measure breast size. Using the tape measure, measure around the diameter of the bust line. Place the tape measure over the fullest part of the breast. Do not press down on the breast, but make sure the tape measure rests comfortably on the breasts. Record this measurement to the nearest inch on paper.

Determine cup size by subtracting the frame measurement from the breast measurement. See the guidelines below to determine cup size. For example, if the frame measurement is 18 inches and the breast measurement is 20 inches, the cup size will be a 2-inch difference, or a B cup.
Cup sizes, according to the online guide My First Bra:

0 to 1/2 inch: AA 1/2 to 1 inch: A 1 to 2 1/2 inches: B 2 1/2 to 3 1/2 inches: C 3 1/2 to 4 1/2 inches: D 4 1/2 to 6 inches: DD (E) 6 to 7 inches: DDD (F) 7 to 8 inches: G

Record cup size, frame size and breast size on a sheet of paper to reference when you go bra shopping.