1/2" BSP parallel (G1/2 / BSPP) (G1/2)
Where G1/2 is used, its real dimensions, and how to connect it to other standards.
G1/2Thread standard
DesignationG1/2
Major diameter20.955 mm
Threads per inch / pitch14
Thread formparallel, 55 degree
Seals onflat washer
Used on: UK indoor taps, washing-machine valves, many mixer-tap tails.
Common indoor UK tap thread. A G1/2 to G3/4 step adapter is the usual way onto a hose fitting.
Quick-connect click fittings from Hozelock, Gardena and Karcher are proprietary and do not interchange. They all sit on top of a standard thread underneath, so the reliable way to move between brands is to adapt at the threaded tap or hose-end fitting, then use each brand's own connector above it.
Connect this thread
Connect Garden Hose Thread (GHT / NH) to 1/2" BSP parallel (G1/2 / BSPP)needs an adapterConnect 1/2" BSP parallel (G1/2 / BSPP) to 3/4" BSP parallel (G3/4 / BSPP)needs an adapterConnect 3/8" BSP parallel (G3/8 / BSPP) to 1/2" BSP parallel (G1/2 / BSPP)needs an adapterConnect 1/2" NPT (National Pipe Taper) to 1/2" BSP parallel (G1/2 / BSPP)needs an adapter1/8" BSP parallel (G1/8 / BSPP)related standard (G1/8)1/4" BSP parallel (G1/4 / BSPP)related standard (G1/4)3/8" BSP parallel (G3/8 / BSPP)related standard (G3/8)3/4" BSP parallel (G3/4 / BSPP)related standard (G3/4)1" BSP parallel (G1 / BSPP)related standard (G1)1-1/4" BSP parallel (G1-1/4 / BSPP)related standard (G1-1/4)
Sources: ISO 228-1 (G / BSPP parallel pipe threads) · BSP thread dimensions chart (ISO 228 / ISO 7), AmesWeb