We just got this suit for our 6-year-old son as a birthday gift. I checked with BJK sizing and measured my little guy before I ordered. We ordered a 4 based on measurements and it fits him great. The material is fantastic, the vest is darling, and my husband is thrilled with the quality. My son is excited to have jacket pockets like Daddy and can't wait to go to the tailor to get the pants hemmed. My only disappointment was the shirt, which is way too tight on the arms, and the tie falls 4 inches short of the waist, not a problem if you always wear the vest, but I was expecting a longer tie. We are very very happy with the 3 main pieces of the suit.