Understanding BSP Thread Sizes
BSP thread sizes are mentioned throughout our site as these are standard thread sizes used throughout the sanitary industry.
This term stands for 'British Standard Pipe' although it is used as an international measure throughout the world.
If you have a fitting and you're not sure what size it is, this simple guide should help
Most common BSP sizes
3/8", 1/2", 3/4", 1", 1.25" & 1.5"
Measuring BSP Sizes
|BSP Size||Diameter of the thread (mm)||Typical products you might find|
|3/8"||15.6||Small caravan taps, European size flexitail connectors|
|1/2"||20.9||Shower hose, valves that screw into sink or basin taps, the rigid tails on basin taps, UK flexitail connectors|
|3/4"||26.4||Bath tap rigid tails, valves that fit into bath taps|
|1.5"||47.8||Bath & sink wastes|
As an example, if you have a 1/2" quarter turn ceramic disk tap valve, the 1/2" refers to the thread on the cartridge that screws into your tap - it is this thread that will measure approx. 20.9mm across
For further reading, we recommend the Wikepedia page
Understanding Tap Nozzle Sizes