it is more correct to compare with the height:
(Unit：CM)
M=3T-4T：length=57 bust=74 shoulder=29 sleeve=41, fits for: 105-115cm height / 3-4 Years Old

L=5T-6T：length=60 bust=78 shoulder=31 sleeve=43, fits for: 115-125cm height / 5-6 Years Old

XL=7T-8T：length=63 bust=82 shoulder=33 sleeve=45, fits for: 125-135cm height / 7-8 Years Old

XXL=9T-10T：length=66 bust=86 shoulder=35 sleeve=47, fits for: 135-145cm 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