it is more correct to compare with the height: (Unit:CM) 90=12M-18M:length=43 bust=60 sleeve=28, fits for: 70-80cm height / 12-18 Months 100=18M-24M:length=46 bust=62 sleeve=30, fits for: 80-90cm height / 18-24 Months 110=3T:length=49 bust=64 sleeve=33, fits for: 90-100cm height / 3 Years Old 120=4T:length=53 bust=68 sleeve=35, fits for: 100-110cm height / 4 Years Old 130=5T:length=56 bust=70 sleeve=38, fits for: 110-120cm height / 5 Years Old 140=6T-7T:length=59 bust=74 sleeve=41, fits for: 120-130cm height / 6-7 Years Old Note: 1.There is 2-3% difference according to manual measurement.(1 inch = 2.54 cm) 2.All measurement in cm, please note 1cm=0.3937ch, 1 inch=2.540cm 3.Please check the figures carefully and order the right size, don't completely depend on the " age advice". It's just for reference.