The size 12Y in Petit Bateau is closest to the following:
Brand Label Weight (lbs) Height (inches)
American Apparel 10 years 54 - 62 lbs 51 - 54 inches
H&M 7-8 years - 50 inches
Hanna Andersson 130cm 52 - 64 lbs 50 - 54 inches
Hatley 12 - 59 inches
LLBean 14-16/L - 59 - 63 inches
Marimekko 11 yrs/ 146 cm - 58 inches
MiniBoden 12y - 60 inches
Petit Bateau 12Y 54 - 58 lbs 59 inches
Ralph Lauren 8/ S 55 - 62 lbs 52 - 54 inches
janie and jack 6 44 - 52 lbs 52 - 62 inches
tea 7/M 51 - 61 lbs 48 - 51 inches