There are formulas out there for measuring yourself to get a bra size, but for many women the result is less than satisfactory. Try fitting by effect rather than fitting by numbers, and see what a difference it makes. You may be surprised at the bra size you end up in!
Start with the Band Size
Just for starters, a tape measure can be handy to determine your band size. This is the measurement straight round your ribcage below your breasts. Hold the tape measure close but not tight. When trying on bras initially, use this measurement as your starting point. If you measured 36 inches around, you will be trying bras labeled 36B, 36C etc until you get the right size. Your bra band should be a close fit but not so tight that you cannot breathe or that it digs in. If it does this, go up a band size.
Choose the right Cup Size
Start with your current newest bra on and look at yourself in the mirror closely. Do your breasts spill over the top or around the sides anywhere? You need to go up at least one cup size. The same is true if the center of the bra doesn't rest flat against your skin.
If the fabric is wrinkled though you may need to go down a size.
Try on several sizes of the same design
Different manufacturers have different cutting standards. Be prepared to try several sizes on when you shop, what is perfect in one make and cut may not fit at all in another manufacturer's design. Don't be at all surprised if your final wardrobe of bras include several wildly different sizes, as long as they fit the body smoothly, create good support and a pleasing silhouette, they are doing their job well.