For most accurate sizing ensure to use proper posture and keep the measuring tape horizontal to the ground while taking your measurements.
Bust: measurement should be taken around the largest part of your chest, without a bra.
Under-bust: measurement should be taken under your breasts where the band of a bra would sit.
Waist: measurement should be taken around the thinnest part of your mid section.
Hip: measurement should be taken around the largest part of your hips/bottom.
These measurements will fall at slightly different places on different bodies.
You may have a waist measurement that indicates one size, while your hip measurement indicates another. Or you may find that your measurements place you between two sizes. It is likely that you would find either of the sizes fit, most people prefer to choose the smaller size for a snugger fit.
Most individuals are comfortable in more than one Aerial Apparel size, which size is best for you will depend on your own fit preferences.
Difference between Under-bust and Bust Measurements
For letter size Aerial Apparel tops, use this chart.