How do you measure the BSP Size?

The easiest way, if you are replacing an existing item is to look at the body of the part to see if the size is stated.

To measure, you need the measure the widest thread on the male thread, see table below.

Metric Name

Β BSPΒ Name

Diameter in mm

Diameter in inches

6mm

1/8” 

9.728mm

0.383

8mm

¼”

13.157mm

0.518

10mm

3/8”

16.662mm

0.656

15mm

½”

20.995mm

0.825

20mm

¾”

26.441mm

1.041

25mm

1”

33.249mm

1.309

32mm

1 ¼”

41.91mm

1.65

40mm

1 ½”

47.803mm

1.882

50mm

2”

59.614mm

2.347

65mm

2 ½”

75.184mm

2.96

75mm or 80mm

3”

87.884mm

3.46

100mm

4”

113.03mm

4.45

125mm

5”

138.43mm

5.45

150mm

6”

163.83mm

6.45