Things You'll Need:
- Flexible tape measure
-
Step 1
Put on a supportive, nonpadded bra to wear while you measure yourself.
-
Step 2
Hold the tape measure flat against your body so it is parallel to the floor and isn't twisted or bunched up anywhere. Wrap the tape measure around your body so it crosses the largest part of your bust. Write the measurement down. If the measurement includes a partial inch, round up to the next whole number. For example, if the number is 36.7 inches, write down 37 inches.
-
Step 3
Using the same method as in Step 2, measure your rib cage just underneath your breasts. Make sure you are not holding your breath and throwing off the measurement, or you will end up with a bra that's too large. Write down this number.
-
Step 4
Take the number from Step 3 and add 4 if it was an even number; add 5 if it was an odd number. For example, if your measurement was 29, you would add 5 to make it 34.
-
Step 5
Subtract the number you got in Step 4 from the number you got in Step 2. In our example, we came up with 37 inches in Step 2 and 34 inches in Step 4. If you subtract 34 from 37, you get 3. The difference between the two numbers represents the cup size.: 1 equals A, 2 equals B and so on. The 3 in our example equates to a C cup. The number in Step 4 also goes into your bra size, so you would be a 34C.
