it is more correct to compare with the height:
(Unit：CM)
110/S=3T-4T：length=52 bust=83 sleeve=42 shoulder=34.5, fits for: 100-110cm height / 3-4 Years Old

120/M=5T：length=55 bust=85 sleeve=44 shoulder=35, fits for: 110-120cm height / 5 Years Old

130/L=6T：length=58 bust=87 sleeve=46 shoulder=35.5, fits for: 120-130cm height / 6 Years Old

140/XL=7T-8T：length=61 bust=89 sleeve=48 shoulder=36, fits for: 130-140cm height / 7-8 Years Old

150/XXL=9T-10T：length=64 bust=91 sleeve=51 shoulder=36.5, 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.