I’m 5’1 and 124 pounds. Ordered a medium and they fit perfectly, so in my opinion that means these run small.
I ordered shorts in white and they are too see through. Manufacturer should have used a thicker facbric. I think I’ll go buy “nude or white boy short undies” to wear under these because you can see my nude thong right through these shorts so bad that a staff member at my gym had to warn me.