The sizes are indicated from S to 4XL, but you would have to speak with a customer service representative to see how each of the sizes equate to specific measurements. For example, I wear XL and my measurements are 40 inch waist and 46 inch chest. I use to wear M when my measurements were 34 waist and 37 chest. The bottoms fit snugly, but do stretch easily, and the tops tend to be loosely comfortable. Hope this helps!