Ordered a medium and it fits just fine - for reference Im 52, 150 pounds, 34C/D, hourglass shape. Perfect size for layering, however if using these as pajamas Id order up a size.

Nice under layer set. Fabric is soft and has just the right amount of stretch.

Knocked a star off because I ordered black, the bag label said black, but the set is definitely navy. Either their black is way off or my bag was mislabeled.