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BSP (British Standard Pipe) is a widely used thread standard in the UK and around the world for pipes and fittings. BSP threads are available in a range of sizes and are used in a variety of applications, from plumbing and gas installations to industrial and hydraulic systems. In this post, we'll explain the basics of BSP pipe and pipe thread sizes and provide tables to help you convert BSP thread sizes to metric.

BSP Pipe Thread Sizes

BSP Size Diameter (mm)
1/8" 9.73
1/4" 13.16
3/8" 16.66
1/2" 20.96
3/4" 26.44
1" 33.25
1 1/4" 41.91
1 1/2" 47.80
2" 59.61

BSP Pipe Thread Pitch

BSP pipe threads have a standard pitch of 14 threads per inch (TPI) for sizes up to 1 inch and 11 TPI for sizes above 1 inch.

BSP Pipe Thread Types

There are two types of BSP pipe threads: parallel and tapered. Parallel threads are used for fittings such as couplings and nipples, while tapered threads are used for joints with a sealant, such as pipe connections to valves and taps


Understanding BSP pipe and thread sizes is essential for anyone working with plumbing and piping systems. By using the tables and charts provided in this article, you can easily convert between BSP and metric measurements and choose the correct pipe and fitting sizes for your project. Whether you are a professional plumber or a DIY enthusiast, having a clear understanding of BSP pipe and thread sizes will make your work more efficient and effective.

At our store, we offer a wide range of BSP pipes and fittings, as well as other plumbing supplies, at competitive prices. Contact us today to learn more about our products and services.

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