You can call this one Rocket science.

If you're the kind of person that doesn't like to go into the lingerie store and have yourself "sized" by one of those bra ladies, then here's the how-to-measure-tutorial from Maidenform that will give you your perfect size.

Grab a soft tape measure. (I tried one of those aluminum retractable ones and almost offed myself.)

BAND MEASUREMENT (the number)
Most women measure their ribcage under their breasts to get their band measurement. Double check this measurement by wrapping a tape measure snugly around your back, under your arms and across the top of your chest above your breasts. Because your ribcage expands and contracts as you breathe, taking both measurements will help you find your most comfortable fit.

CUP MEASUREMENT (the letter)
With your bra on, wrap a measuring tape around your back and across the fullest part of your breast. Don't pull too tight! To find your cup size, subtract your band measurement from this measurement.

If the difference is...

1 inch, you're an A cup
2 inches, a B cup
3 inches, a C cup
4 inches, a D cup
5 inches, a DD cup
6 inches, a DDD cup

So if your cup measurement is 39 inches and your band size is 36 inches, the 3 inch difference makes you a 36C.

For pictures and the full international sizing chart, click here.