Back of Pack Sizes: 1-3 (small) 34-40 inches/17-37 lbs. 4-5 (small) 37-48 inches / 38-55 lbs. 6-8 (medium) 46-56 inches / 56-80 lbs. 10-12 (Large) 57-60 inches / 81-110 lbs. My very tall 4 year old is 43" tall with a 20" inseam. Size 4-5 (small) was difficult to put on, very tight fit. 6-8 (medium) suits her perfectly with some room to grow. I wash them in a mesh laundry bag (although hand washing is recommended) and let them air dry and have had no problems as these are very durable tights.