it is more correct to compare with the height:
(Unit: CM)
M/120=4T-5T：length=69 bust=78 sleeve=50, fits for: 105-120cm height / 4-5 Years Old

L/130=6T：length=73 bust=82 sleeve=53, fits for: 120-125cm height / 6 Years Old

XL/140=7T-8T：length=77 bust=86 sleeve=57, fits for: 125-135cm height / 7-8 Years Old

XXL/150=9T-10T：length=82 bust=90 sleeve=61, fits for: 135-145cm height / 9-10 Years Old

XXXL/160=11T-12T：length=86 bust=94 sleeve=65, 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.