it is more correct to compare with the height:
(Unit：CM)
120/M=5T：length=61 bust=79 sleeve=45, fits for: 110-120cm height / 5 Years Old

130/L=6T：length=65 bust=83 sleeve=48, fits for: 120-130cm height / 6 Years Old

140/XL=7T-8T：length=69 bust=87 sleeve=51, fits for: 130-140cm height / 7-8 Years Old

150/XXL=9T-10T：length=73 bust=91 sleeve=54, fits for: 140-150cm height / 9-10 Years Old

160/XXXL=11T-12T：length=77 bust=95 sleeve=57, fits for: 150-160cm 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.