it is more correct to compare with the height:
(Unit：CM)
110=4T：Tops length=29 bust=92 sleeve=33 Pants length=66 waist=42 hips=92, fits for: 100-110cm height / 4 Years Old

120=5T：Tops length=31 bust=98 sleeve=36 Pants length=73 waist=46 hips=96, fits for: 110-120cm height / 5 Years Old

130=6T：Tops length=33 bust=102 sleeve=39 Pants length=79 waist=48 hips=100, fits for: 120-130cm height / 6 Years Old

140=7T-8T：Tops length=35 bust=108 sleeve=42 Pants length=86 waist=52 hips=104, fits for: 130-140cm height / 7-8 Years Old

150=9T-10T：Tops length=37 bust=112 sleeve=45 Pants length=92 waist=54 hips=108, fits for: 140-150cm height / 9-10 Years Old

S=11T-12T：Tops length=41 bust=118 sleeve=50 Pants length=101 waist=60 hips=114, fits for: 150-160cm height / 11-12 Years Old

M=13T-14T：Tops length=43 bust=124 sleeve=53 Pants length=105 waist=62 hips=118, fits for: 160-170cm 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.