My daughter saw this and fell in love with the costumes. My daughter is a UK size 4-6 and we got a ladies small it was a little loose but with leggins and long sleeve shirt it actually fit her well with a bit bit of room for growth. Based on how it fit a asmall would fit a UK Size 8 perfectly. Its love stretchy polyester/spandex. Keep in mind this does have specific washing instructions. Hand wash only and no tumble dryer. It will damage the costume. I do recommend it as it is well printed and colors are very vibrant.