British Pipe Standard
The British Standard Pipe (BSP) is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread and has been adopted as a standard scale used in plumbing fittings, except in the United States where NPT is the standard used.
Measuring the Outside of the Male Thread:
- 9.5mm (3/8") External Diameter — Male 1/8" BSP Thread
- 13mm (1/2") External Diameter — Male 1/4" BSP Thread
- 16mm External Diameter — Male 3/8" BSP Thread
- 21mm (5/8") External Diameter — Male 1/2" BSP Thread
- 26mm (1") External Diameter — Male 3/4" BSP Thread
- 37mm External Diameter — Male 1" BSP Thread
Measuring the Inside of the Female Thread:
- 8mm Internal Diameter — Female 1/8" BSP Thread
- 11.5mm (3/8") Internal Diameter — Female 1/4" BSP Thread
- 14mm Internal Diameter — Female 3/8" BSP Thread
- 19mm (3/4") Internal Diameter — Female 1/2" BSP Thread
- 24.5mm (5/8") Internal Diameter — Female 3/4" BSP Thread
- 31mm Internal Diameter — Female 1" BSP Thread
Threads are tapered to ensure a water tight seal so sizes are approximate