it is more correct to compare with the height:
(Unit:CM)
100=2T-3T:length=46 waist=42 hips=72; fits for: 90-100cm height / 2-3 Years Old
110=4T:length=50 waist=44 hips=76; fits for: 100-110cm height / 4 Years Old
120=5T:length=54 waist=46 hips=78; fits for: 110-120cm height / 5 Years Old
130=6T:length=58 waist=48 hips=80; fits for: 120-130cm height / 6 Years Old
140=7T:length=62 waist=50 hips=88; fits for: 130-140cm height / 7 Years Old
150=8T:length=66 waist=54 hips=96; fits for: 140-150cm height / 8 Years Old
160=9T-10T:length=71 waist=56 hips=100; fits for: 150-160cm height / 9-10 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.