Different companies usually run different sizes, so please do check and compare your measurements of bust, waist, hip(widest part of hip including butt) and hollow to floor with shoes on with our Fit&Sizing Guide before deciding your size. Only error is less than 1'' between your real measurements and standard size, then choose standard size otherwise it's better custom size. The measurements on the size chart are body measurements, not finished dress measurements.
US 
UK