it is more correct to compare with the height:
Unit：CM
90=2T：length=45 bust=72 shoulder=34 sleeve=26, fits for: 80-90cm height / 2 Years Old

100=3T：length=48 bust=76 shoulder=36 sleeve=28, fits for: 90-100cm height / 3 Years Old

110=4T：length=51 bust=80 shoulder=37 sleeve=31, fits for: 100-110cm height / 4 Years Old

120=5T：length=54 bust=84 shoulder=39 sleeve=33, fits for: 110-120cm height / 5 Years Old

130=6T：length=57 bust=88 shoulder=40 sleeve=36, fits for: 120-130cm height / 6 Years Old

140=7T：length=60 bust=92 shoulder=42 sleeve=38, fits for: 130-140cm height / 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.