Each listing has the exact size measurements for that specific garment. The measurements are taken while the garment is laying flay on a surface. Use your garment measuring tape to multiply the bust x 2 and that is the circumference. Same for circumference of hips.  If you do not have a garment tape measure we recommend this one for under $3. Garment Tape Measure

SIZE CHARTS

US UK AUS
XS 2-4 6 6
S 4-6 8 8
M 6-8 10 10
L 8-10 12 12
XL 10-12 14 14