it is more correct to compare with the height:
(Unit：CM)
120=5T：Tops length=39 Pants length=75 waist=48 hips=100, fits for: 110-120cm height / 5 Years Old

130=6T：Tops length=42 Pants length=80 waist=50 hips=104, fits for: 120-130cm height / 6 Years Old

140=7T-8T：Tops length=44 Pants length=85 waist=52 hips=108, fits for: 130-140cm height / 7-8 Years Old

150=9T-10T：Tops length=47 Pants length=90 waist=54 hips=112, fits for: 140-150cm height / 9-10 Years Old

160=11T-12T：Tops length=49 Pants length=95 waist=56 hips=116, fits for: 150-160cm height / 11-12 Years Old

170=13T-14T：Tops length=52 Pants length=100 waist=58 hips=120, fits for: 160-165cm 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.