it is more correct to compare with the height:
(Unit：CM)
100=3T：length=40 bust=82 sleeve=34 shoulder=43, fits for: 90-100cm height / 3 Years Old

110=4T：length=42 bust=86 sleeve=36 shoulder=45, fits for: 100-110cm height / 4 Years Old

120=5T：length=44 bust=90 sleeve=37 shoulder=47, fits for: 110-120cm height / 5 Years Old

130=6T：length=46 bust=94 sleeve=38 shoulder=49, fits for: 120-130cm height / 6 Years Old

140=7T-8T：length=48 bust=98 sleeve=39 shoulder=51, fits for: 130-140cm height / 7-8 Years Old

150=9T-10T：length=50 bust=102 sleeve=40 shoulder=55, fits for: 140-150cm height / 9-10 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.