Always pull the tape measure snug, but not tight. If you do not have a tape measure, use string and then measure the string with a ruler.
Bust: Measure around the fullest part of your bust. If you will be wearing foundation garments under the costume, wear those while measuring.
Waist: Measure the narrowest part of your waist, typically at the belly button.
Hips: Measure around the fullest part of your hips and tush, not up around your hip bones.
Girth: Place the tape measure at your shoulder where a bra strap would lie. Measure down your body, between your legs, and up your back to where the tape measure began.
If you feel you have an unusual sizing, please include measurements or a description. I am always happy to custom size for you! There is no additional charge for custom sizing.