The size 16-18/XL in LLBean is closest to the following:
Brand Label Weight (lbs) Height (inches)
American Apparel 12 years 62 - 75 lbs 55 - 59 inches
Hanna Andersson 160cm 88 - 110 lbs 62 - 66 inches
Hatley 12 - 59 inches
J.Crew/ Crewcuts 16 110 - 125 lbs 64 - 68 inches
LLBean 16-18/XL - 64 inches
Marimekko 12 yrs/ 152 cm - 61 inches
MiniBoden 12y - 60 inches
Petit Bateau 12Y 54 - 58 lbs 59 inches
Ralph Lauren 18/ XL 116 - 126 lbs 64 - 66 inches
The Children's Place 0-3 months 7 - 11 lbs -
janie and jack 7 52 - 62 lbs 62 - 74 inches
tea 12/XL 82 - 95 lbs 57 - 60 inches