it is more correct to compare with the height:
(Unit：CM)
Size 90=2T：Top length=24 Bust=64 skirt=28 sleeve=31, fits for: 75-85cm height / 2 Years Old

Size 100=3T：Top length=26 Bust=67 skirt=30 sleeve=34, fits for: 85-95cm height / 3 Years Old

Size 110=4T：Top length=28 Bust=70 skirt=32 sleeve=37, fits for: 95-105cm height / 4 Years Old

Size 120=5T：Top length=30 Bust=74 skirt=35 sleeve=40, fits for: 105-115cm height / 5 Years Old

Size 130=6T：Top length=32 Bust=78 skirt=37 sleeve=43, fits for: 115-125cm height / 6 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.