it is more correct to compare with the height:
(Unit: CM)
130/3=5T-6T：length=56 bust=108 sleeve=40 shoulder=45; fits for: 115-125cm height / 5-6 Years Old

140/4=7T-8T：length=59 bust=102 sleeve=43 shoulder=47; fits for: 125-135cm height / 7-8 Years Old

150/5=9T-10T：length=62 bust=106 sleeve=46 shoulder=49; fits for: 135-145cm height / 9-10 Years Old

160/6=11T-12T：length=65 bust=120 sleeve=48 shoulder=51; fits for: 145-155cm height / 11-12 Years Old

170/7=13T-14T：length=68 bust=124 sleeve=51 shoulder=52; fits for: 155-165cm 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.