Following guidelines would be helpful to determine right wear size for you.
HOW TO MEASURE FOR TOP
Wearing a non-padded, non-minimizing everyday bra, measure just above the bust by bringing a soft measuring tape across your back at band level, under each arm (elbows down), then around the front to snugly but comfortably line up with where your bra straps meet your cups.
TIP: Odd number or on the half inch? Round down to the nearest even number.
TIP: Did you measure yourself below the bust instead? Follow our guidelines for above-the-bust measuring before entering your Band Size into the Perfect Fit Calculator.
Measure across the fullest part of the bust by threading a soft measuring tape across your back at band level and under each arm, being careful that your elbows are down and that the tape isn't pulled away from the body in the front.
With the tape in position, take a breath in and out, allowing it to slide to its most comfortable, non-binding fit.
TIP: If the measurement falls on the half inch, round up.
HOW TO MEASURE FOR BOTTOM
Bend to one side to find a natural indentation in torso. This is your natural waist. Run tape around natural waistline, keeping tape parallel with floor and one finger between body and tape for a more comfortable fit.
Stand on a level surface with feet together. Measure around fullest part of hips and bottom (approximately 7"-9" below waistline), keeping tape parallel with floor
As per U.S size or specific bust, waist and hips measurement, you can choose the corresponding right size like S, M, L, XL and further plus sizes for you.