it is more correct to compare with the height:
(Unit:CM)
120=5T:Length=53 Bust=74 Sleeve=41 Shoulder=33, fits for: 110-120cm height / 5 Years Old

130=6T:Length=56 Bust=78 Sleeve=42 Shoulder=35, fits for: 120-130cm height / 6 Years Old

140=7T-8T:Length=59 Bust=82 Sleeve=44 Shoulder=37, fits for: 130-140cm height / 7-8 Years Old

150=9T-10T:Length=62 Bust=86 Sleeve=46 Shoulder=38, fits for: 140-150cm height / 9-10 Years Old

160=11T-12T:Length=65 Bust=90 Sleeve=47 Shoulder=39, fits for: 150-155cm height / 11-12 Years Old

170=13T-14T:Length=69 Bust=94 Sleeve=48 Shoulder=40, fits for: 155-160cm height / 13-14 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.