it is more correct to compare with the height:
80=9M/12M：Top length=36 bust=58 Pants length=46, fits for: 66-75cm height / 6-12 Months
90=18M：Top length=38 bust=60 Pants length=49, fits for: 75-85cm height / 12-18 Months
100=24M：Top length=40 bust=62 Pants length=52, fits for: 85-95cm height / 18-24 Months
110=3T：Top length=42 bust=64 Pants length=55, fits for: 95-105cm height / 3-4 Years Old
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.