Just when you get to memorise the size of something, you go to a different country  and....they use a different system. So here's a shoe conversion chart. Boys and Girls Conversion Chart

Inches

US / Canada

Europe

Japan

UK

5.38

6.5

23

-

5.5

5.56

7

23.5

14

6

5.75

7.5

24

-

6.5

5.88

8

24.5

15

7

6.06

8.5

25

-

7.5

6.25

9

25.5

16

8

6.38

9.5

26

-

8.5

6.47

10

26.5

16.5

9

6.67

10.5

27

-

9.5

6.83

11

27.5

17.5

10

6.98

11.5

28

-

10.5

7.14

12

28.5

18.5

11

7.30

12.5

29

-

11.5

7.46

13

30

19

12

7.77

1

31

20

13

7.93

1.5

31.5

20.5

13

8.09

2

32.5

21

1

8.25

2.5

33

21.5

1.5

8.40

3

33.5

22

2

Women's International Shoe Size Conversion Chart

US / Canada

China

Australia

Europe

Mexico

Japan

UK

5

35.5

3.5

35

-

21

2.5

5.5

36

4

35.5

-

21.5

3

6

37

4.5

36

-

22

3.5

6.5

37.5

5

37

-

22.5

4

7

38

5.5

37.5

-

23

4.5

7.5

39

6

38

4.5

23.5

5

8

39.5

6.5

38.5

5

24

5.5

8.5

40

7

39

5.5

24.5

6

9

41

7.5

40

6

25

6.5

9.5

-

8

41

6.5

25.5

7

10

42

8.5

42

7

26

7.5

Men's International Shoe Sizes

US / Canada

China

Australia

Europe

Mexico

Japan

UK

5

38

4.5

37.5

-

-

4.5

5.5

39

5

38

-

-

5

6

39.5

5.5

38.5

25

24

5.5

6.5

40

6

39

-

24.5

6

7

41

6.5

40

26

25

6.5

7.5

-

7

40.5

-

25.5

7

8

42

7.5

41

27

-

7.5

8.5

43

8

42

-

26

8

9

43.5

8.5

42.5

28

26.5

8.5

9.5

44

9

43

-

27

9

10

44.5

9.5

44

29

27.5

9.5

10.5

45

10

44.5

-

28

10

11

46

-

45

30

29

10.5

11.5

-

11

45.5

-

29.5

-

12

47

-

46

31

30

-

13

48.5

12

47.5

32

31

-