Getting your daughter or granddaughter her first bra is a treasured milestone for you, but may be an uncomfortable and embarrassing ordeal for her. To ease some of the preteen pain, you may want to measure her yourself in the privacy of your own home. While many women wear the wrong bra size, your daughter doesn't have to. Measuring her for a correct fit is a relatively simple procedure.
Have teen put on undershirt or tank top. Fittings are traditionally done in a bra that fits already, but because this is her first bra, a close-fitting shirt will suffice.
Measure for band size. Have the girl exhale and slightly raise her arms. Wrap the measuring tape around her ribcage, directly under the bust, keeping measuring tape straight, untwisted and firm against the body.
Jot down the band size measurement on the paper. If the number is a fraction, round it down to the next lowest whole number.
Add 4 inches to this number if it is an even number (for example, a band measurement of 30 inches would become 34 inches) or add 5 inches if it is an odd number (for example, a band measurement of 31 inches would become 36 inches).
Measure for cup size. Have teen stand straight with arms loosely at side. Measure around the fullest part of the bust with the measuring tape. Unlike measuring for band size, do not pull measuring tape too firmly---tape should be untwisted and have contact with the teen's body all the way around, but not be binding.
Jot down the cup measurement.
Calculate bra size. Subtract the adjusted band measurement you found in step 4 from the cup measurement you measured in step 5. This difference will determine the bra size (for every inch of difference, cup size increases: A is equal to 1 inch, B is equal to 2 inches, C is equal to 3 inches, and so forth). For example, if you determined that the teen's band size was 34 inches (30 inches of measurement plus the added 4), and her cup measurement was 36 inches, subtracted that would leave a difference of 2 inches or a B cup. The correct bra size would be 34B. Refer to the conversion chart in resources for more assistance.
As sizes increase above D, it can become more difficult to buy a properly-fitting bra based solely on sizing by measurement. Have the teen try on multiple bras for fit and comfort.