it is more correct to compare with the height:
(Unit：CM)
120=4T-5T：Top length=46.5 bust=75 sleeve=45 Pants length=71 waist=24, fits for: 110-120cm height / 4-5 Years Old

130=6T：Top length=49.5 bust=79 sleeve=48 Pants length=76 waist=25, fits for: 120-130cm height / 5-6 Years Old

140=7T：Top length=52.5 bust=83 sleeve=51 Pants length=81 waist=26, fits for: 130-140cm height / 6-7 Years Old

150=8T：Top length=55.5 bust=87 sleeve=54 Pants length=86 waist=27, fits for: 140-145cm height / 7-8 Years Old

160=9T-10T：Top length=58.5 bust=91 sleeve=57 Pants length=91 waist=28, fits for: 145-150cm height / 9-10 Years Old

170=11T-12T：Top length=61.5 bust=95 sleeve=60 Pants length=96 waist=30, fits for: 150-155cm 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.