Measure your exact ring size with this ring sizing set. The individual rings can be snapped out of the plastic sheet to allow for an exact measurement. Use the little belt type sizer to double check on the size and to hold the individual blue plastic rings neatly together. This little belt sizer works for sizes 1 - 17, so no matter if your size is tiny or xxl, this sizer will help you get the correct measurement. 
 

Simply slip the end thru the buckle, and tighten it until you get a comfortable fit, then read the size indicated by the arrow.