it is more correct to compare with the height:
(Unit: CM)
90=2T：length=39 bust=70 sleeve=36 shoulder=28, fits for: 80-90cm height / 2 Years Old

100=3T：length=42 bust=74 sleeve=38 shoulder=30, fits for: 90-100cm height / 3 Years Old

110=4T：length=45 bust=78 sleeve=40 shoulder=32, fits for: 100-110cm height / 4 Years Old

120=5T：length=48 bust=82 sleeve=42 shoulder=33, fits for: 110-120cm height / 5 Years Old

130=6T：length=51 bust=86 sleeve=45 shoulder=35, fits for: 120-130cm height / 6 Years Old

140=7T-8T：length=54 bust=90 sleeve=47 shoulder=37, fits for: 130-135cm height / 7-8 Years Old

150=9T-10T：length=57 bust=94 sleeve=50 shoulder=39, fits for: 135-145cm height / 9-10 Years Old

160=11T-12T：length=60 bust=98 sleeve=53 shoulder=41, fits for: 145-155cm height / 11-12 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.