child size reference table:
US shoe size	European	Heel to the toes (cm)
9	26	16.5
10	27	17.0
11	28	17.5
11.5	29	18.0
12.5	30	18.5
13.5	31	19.0
1	32	19.5
2	33	20.0
3	34	20.5
3.5	35	21.1
4.5	36	21.8
Note: please allow 0.3 cm error due to manual measurement