it is more correct to compare with the height:
(Unit:CM)
90=12M-18M:length=42 bust=76 sleeve=31, fits for: 80-90cm height / 12-18 Months
100=18M-24M:length=45 bust=80 sleeve=34, fits for: 90-100cm height / 18-24 Months
110=3T:length=48 bust=84 sleeve=36, fits for: 100-110cm height / 3 Years Old
120=4T:length=51 bust=88 sleeve=39, fits for: 110-120cm height / 4 Years Old
130=5T:length=54 bust=92 sleeve=41, fits for: 120-125cm height / 5 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.