Pick the dress that fits you best, button it up and lay it face up on the kitchen table (sample note).
Measure the length from the top of the shoulder beside the collar to the hem, the chest from armpit to armpit, the sleeve from the shoulder seam, and the hem straight across. Write the numbers down.
Compare them with the table on any of our piece pages. Within two centimetres across the chest is usually the same fit; more than that, ask us and we will check the next size for you.