How to convert inches to millimeters?

Size in "

diameter (mm) male thread pipe size

1/8”

10,20

1/4"

13,50

3/8”

17,20

1/2"

21,30

3/4"

26,60

1”

33,70

1 1/4"

42,40

1 1/2"

48,30

2”

60,30

2 1/2"

76,10

3”

88,90

4”

114,30

5”

139,70

6”

168,30