it is more correct to compare with the height:
(Unit：CM)
Size 120=4T：Length=60 Bust=83 Sleeve=45 Shoulder=34, fits for: 110-115cm height / 4 Years Old

Size 130=5T-6T：Length=63 Bust=86 Sleeve=47 Shoulder=35, fits for: 115-125cm height / 5-6 Years Old

Size 140=7T-8T：Length=66 Bust=89 Sleeve=49 Shoulder=36, fits for: 125-135cm height / 7-8 Years Old

Size 150=9T-10T：Length=69 Bust=92 Sleeve=51 Shoulder=37, fits for: 135-145cm height / 9-10 Years Old

Size 160=11T-12T：Length=72 Bust=95 Sleeve=53 Shoulder=38, fits for: 145-155cm height / 11-12 Years Old

Size 170=13T-14T：Length=75 Bust=98 Sleeve=55 Shoulder=39, 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.