it is more correct to compare with the height:
(Unit:CM)
Size 110=3T:Length=59 Bust=80 Sleeve=41 Shoulder=31, fits for: 95-105cm height / 3 Years Old
Size 120=4T:Length=62 Bust=82 Sleeve=43 Shoulder=32, fits for: 105-115cm height / 4 Years Old
Size 130=5T-6T:Length=65 Bust=84 Sleeve=45 Shoulder=33, fits for: 115-125cm height / 5-6 Years Old
Size 140=7T-8T:Length=68 Bust=86 Sleeve=47 Shoulder=34, fits for: 125-135cm height / 7-8 Years Old
Size 150=9T-10T:Length=71 Bust=88 Sleeve=49 Shoulder=35, fits for: 135-145cm height / 9-10 Years Old
Size 160=11T-12T:Length=74 Bust=90 Sleeve=51 Shoulder=36, fits for: 145-150cm 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.