No size marking, but closed tight the waist is 27" - that is the tightest the waist will cinch.

This would fit a size 27-30" waist best in my opinion.  Since the corset is mostly comprised of plastic boning, I don't feel this will do any major cinching, but it will shape you nicely.  The bottom, hip line of the corset measures 32" around laced tight.  

The corset is 14" long in front and 10" long at the sides and in back.