Put on your best fitting non padded bra. While wearing a bra place the tape measure around your rib cage just below the bust under the bottom bra edge. The grey cells in the table below demonstrate how the sizes diagonally adjacent from the top right to the bottom left are the same in breast volume ie. Add 5 inches to that measurement to determine your bra size. Straighten the tape so that its parallel to the floor. Your bra size is a us 36ddddg.
Thats a 7 difference or a ddddg cup. Its dealing with bra sizes and rib cage size. Lets say your underbust measurement is 35 and your overbust measurement is 42. Bra band sizes go in 2 inch increments. Make sure the measuring tape is straight and level. Your underbust measurement is odd so you add 1 leading to a band size of 36.
The same volume of breast tissue spread across different size rib cages band sizes. While braless or wearing a non padded bra take a measuring tape and measure snugly around your torso directly under your bust at your rib cage. You can check the bra sizes chart or calculator further up this page to confirm your correct. It uses your rounded underbust measurement as your band measurement. Exhale deeplyyou want the smallest measurement possible. Wrap a measuring tape snugly around your rib cage just beneath your bustline.
Bust measurement 43 inches rib cage measurement 36 inches difference of 7 inches so d cup. That measurement in inches will determine your cup and frame size. For example the bcd might be 40 and the rib cage of 32. Your band size should essentially be your underbust measurement more on that in the next section rounded to the nearest inch. I cant find the average ribcage size for women. I wear a 28g and this fits perfectly but my actual rib cage measurement is 24inches but should i actually find a very rare 26 band bra although it does up fine it does tend to poke into my ribs and ache at the end of the day so 28 is better.
The combination of bcd and rib cage is your pattern size. If you look at bra size charts that take the measurement directly it always tells you to take the measurement wearing a bra that fits. So 28 inches 30 inches 32 inches and so on. Ensure a good sports bra fit now that youve figured out your estimated band and cup size its time to try on several different brands and styles of sports bras to test the fit. Then take your rib cage measurement directly under your bra. Round to the nearest whole number and refer to the size chart below.
Make sure the tape is comfortably snug and take your measurement to the fullest inch. That actual rib cage measurement no magic number involved is used for the band length. I think this is right you just have to try them on until one fits. Im 30 in when i measure under my breasts and im 5ft 7in. Bra sizes that are the same in volume are often referred to as sister sizes.