it is more correct to compare with the height:
(Unit：CM)
100=3T：length=40 bust=36 shoulder=32 sleeve=32, fits for: 85-95cm height / 3 Years Old

110=4T：length=43 bust=37 shoulder=33 sleeve=35, fits for: 95-105cm height / 4 Years Old

120=5T：length=46 bust=39 shoulder=34 sleeve=38, fits for: 105-115cm height / 5 Years Old

130=6T：length=49 bust=41 shoulder=35 sleeve=40, fits for: 115-125cm height / 6 Years Old

140=7T-8T：length=52 bust=43 shoulder=37 sleeve=43, fits for: 125-135cm height / 7-8 Years Old

150=9T-10T：length=55 bust=45 shoulder=38 sleeve=47, fits for: 135-145cm height / 9-10 Years Old

160=11T-12T：length=58 bust=47 shoulder=39 sleeve=51, fits for: 145-155cm 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.