I think the Munkimunki size from MM web page may be more accurate. STP shows XS to be size 2-4, MM shows XS to be 0-2. I compared my MunkiMunki XS to my Calida XS, and the Calida nightgown is roomier. I can wear both, but MunkiMunki XS is smaller. Since the sizes overlap (0-2, 2-4), the difference is not as great as the XL charts of 12-14, or 16-18. Maybe look at the actual measurements on MM web page. Hope this helps.