I ordered a size 6 for my 4 year old (who is tall for his age) and it fit great with a little room to grow. After reading other reviews, I thought it best to go a size or two up and I'm glad I did. The material is super soft and great quality. Even better than I expected. My son loves his new, comfy dinosaur pajamas. Washed in cold, material maintained size and softness. Very pleased with this purchase!