it is more correct to compare with the height:
(Unit：CM)
90=18M-24M：length=39 bust=48 shoulder=29 sleeve=32, fits for: 75-85cm height / 18-24 Months

100=3T：length=41 bust=51 shoulder=30 sleeve=34, fits for: 85-95cm height / 2-3 Years Old

110=4T：length=44 bust=54 shoulder=31 sleeve=36, fits for: 95-105cm height / 3-4 Years Old

120=5T：length=47 bust=57 shoulder=32 sleeve=38, fits for: 105-115cm height / 4-5 Years Old

130=6T：length=50 bust=60 shoulder=34 sleeve=40, fits for: 115-125cm height / 5-6 Years Old

140=7T-8T：length=53 bust=63 shoulder=36 sleeve=42, fits for: 125-135cm height / 7-8 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.