BSP Thread Chart
A BSP thread chart provides crucial dimensions and specifications for British Standard Pipe threads. We offer a wide range of BSP fittings and components, all manufactured to the highest industry standards.
British Standard Pipe Parallel / British Standard Pipe Taper
55 Degree Threads
SIZE | TPI | MAJOR (EXT) | MINOR (INT) | TAP DRILL |
1/8″ | 28 | 9.728 | 8.566 | 8.70 |
1/4″ | 19 | 13.157 | 11.445 | 11.60 |
3/8″ | 19 | 16.662 | 14.950 | 15.00 |
1/2″ | 14 | 20.955 | 18.631 | 19.00 |
5/8″ | 14 | 22.911 | 20.587 | 20.75 |
3/4″ | 14 | 26.441 | 24.117 | 24.50 |
7/8″ | 14 | 30.201 | 27.877 | 28.00 |
1″ | 11 | 33.249 | 31.770 | 30.50 |
11/8″ | 11 | 37.897 | 34.939 | 35.00 |
11/4″ | 11 | 41.910 | 38.952 | 39.50 |
13/8″ | 11 | 44.323 | 41.365 | 41.50 |
11/2″ | 11 | 47.803 | 44.845 | 45.00 |
13/4″ | 11 | 53.746 | 50.788 | 51.00 |
2″ | 11 | 59.614 | 56.656 | 57.00 |
21/4″ | 11 | 65.710 | 62.752 | 63.00 |
21/2″ | 11 | 75.184 | 72.226 | 72.50 |
23/4 | 11 | 81.534 | 78.576 | 79.00 |
3″ | 11 | 87.884 | 84.926 | 85.50 |
31/4″ | 11 | 93.980 | 91.501 | 91.00 |
31/2″ | 11 | 100.330 | 97.372 | 97.75 |
33/4″ | 11 | 106.680 | 103.722 | 104.00 |
4″ | 11 | 113.030 | 110.072 | 110.50 |
41/2″ | 11 | 125.730 | 122.772 | 123.00 |
5″ | 11 | 138.430 | 135.472 | 136.00 |
51/2″ | 11 | 151.130 | 148.172 | 148.50 |
6″ | 11 | 163.830 | 160.872 | 161.50 |
NOTE: G = BSPP / R = BSPT
All Threads
BSP Thread
BSP, which stands for British Standard Pipe, refers to a family of thread standards used for connecting pipes and fittings. These standards encompass both tapered and parallel thread profiles. BSP threads are widely adopted internationally, particularly in countries outside of North America.
The most common types of BSP threads are:
- BSPT (British Standard Pipe Tapered): These threads feature a tapered profile, similar to NPT threads, and rely on the taper for sealing.
- BSPP (British Standard Pipe Parallel): These threads have a parallel profile and typically utilize separate sealing components like washers or O-rings.
BSP threads are crucial for ensuring compatibility and proper function in various applications, including plumbing, hydraulics, and pneumatics.
British Standard Pipe Parallel Thread (BSPP)
BSPP stands for British Standard Pipe Parallel. It’s a type of thread profile commonly used in plumbing, hydraulics, and pneumatic systems. Unlike BSPT (British Standard Pipe Tapered) which uses the taper of the thread for sealing, BSPP employs separate sealing components such as washers or O-rings to ensure a reliable and consistent seal. This makes BSPP particularly suitable for high-pressure applications and situations where frequent assembly and disassembly are required.
British Standard Pipe Taper Thread (BSPT)
BSPT, which stands for British Standard Pipe Taper, is a thread standard commonly used in plumbing, hydraulics, and pneumatic systems. It features a 55-degree thread angle and a slight taper on the male thread. This taper, combined with the application of thread sealants such as Teflon tape or pipe dope, creates a tight seal when the male thread is screwed into the female counterpart.
BSPT threads are known for their reliability and are widely used in various applications, including general plumbing, hydraulic systems, and industrial machinery.
Please note: BSPT is distinct from BSPP (British Standard Pipe Parallel), which features parallel threads and relies on separate sealing components like washers or O-rings.
Thread Count (TPI)
Thread count, often expressed as TPI (threads per inch), refers to the number of complete threads within a one-inch length along the threaded portion of a fastener or pipe.
A higher thread count generally indicates finer threads with smaller pitches.
Thread count significantly influences the characteristics of a threaded connection. Higher thread counts typically result in:
- Finer Pitch: Smaller distance between threads.
- Increased Strength: More threads engage, distributing the load over a larger area.
- Improved Sealing: In some cases, finer threads can enhance sealing capabilities.
However, higher thread counts can also have limitations:
- Reduced Resistance to Vibration: Finer threads may be more susceptible to loosening under vibration.
- Increased Difficulty in Assembly: Assembling and disassembling components with high thread counts can be more challenging.
The appropriate thread count depends on the specific application and its requirements. Factors such as the strength requirements, vibration levels, and ease of assembly should be considered when selecting the optimal thread count.
BSP Thread Chart

British Standard Pipe Parallel Thread Chart | BSPP Thread Chart
Size | Pitch | External Thread OD | Internal Thread ID | ||
---|---|---|---|---|---|
inch | TPI | mm | inch | mm | inch |
1/8″ | 28 | 9.6 | 0.38 | 8.6 | 0.34 |
1/4″ | 19 | 13.0 | 0.51 | 11.9 | 0.47 |
3/8″ | 19 | 16.5 | 0.65 | 15.2 | 0.6 |
1/2″ | 14 | 20.8 | 0.82 | 19.1 | 0.75 |
5/8″ | 14 | 22.8 | 0.9 | 20.8 | 0.82 |
3/4″ | 14 | 26.3 | 1.04 | 24.6 | 0.97 |
1″ | 11 | 31.1 | 1.3 | 30.7 | 1.21 |
1-1/4″ | 11 | 41.8 | 1.64 | 39.4 | 1.55 |
1-1/2″ | 11 | 47.7 | 1.88 | 45.5 | 1.79 |
2″ | 11 | 59.5 | 2.34 | 57.4 | 2.26 |
2-1/2″ | 11 | 75.1 | 2.95 | 72.6 | 2.86 |
3″ | 11 | 87.9 | 3.46 | 85.4 | 3.36 |
British Standard Pipe Taper Thread Chart | BSPT Thread Chart
Size | Pitch | External Thread OD | Internal Thread ID | ||
---|---|---|---|---|---|
inch | TPI | mm | inch | mm | inch |
1/8″ | 28 | 9.5 | 0.37 | 8.4 | 0.33 |
1/4″ | 19 | 12.8 | 0.5 | 11.2 | 0.44 |
3/8″ | 19 | 16.3 | 0.64 | 14.7 | 0.59 |
1/2″ | 14 | 20.4 | 0.8 | 18.3 | 0.72 |
5/8″ | 14 | 22.5 | 0.89 | 20.6 | 0.81 |
3/4″ | 14 | 25.9 | 1.02 | 23.9 | 0.94 |
1″ | 11 | 32.6 | 1.28 | 29.7 | 1.17 |
1-1/4″ | 11 | 41.1 | 1.62 | 38.6 | 1.52 |
1-1/2″ | 11 | 47.0 | 1.85 | 44.5 | 1.75 |
2″ | 11 | 58.6 | 2.31 | 56.4 | 2.22 |
2-1/2″ | 11 | 74.1 | 2.92 | 71.9 | 2.83 |
3″ | 11 | 86.6 | 3.41 | 84.6 | 3.33 |