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Thread Size Tables
View Our OnlineThread Size Tables
Back to help centreView our handy online thread size tables to help you find all the information you need about the valve or pipe threads you are working with. Our tables cover thread size, threads per inch, pitch and thread diameter. We have thread tables for both British Standard Pipe (BSP) and National Pipe Thread (NPT). Find the thread table you need below.
| BSP THREAD SIZES | ||||
|---|---|---|---|---|
| Thread Size [inches] |
Threads Per Inch |
Pitch [mm] |
Major Diameter Of The Thread | |
| mm | inches | |||
| 1/8 | 28 | 0.907 | 9.723 | 0.383 |
| 1/4 | 19 | 1.337 | 13.157 | 0.518 |
| 3/8 | 19 | 1.337 | 16.662 | 0.656 |
| 1/2 | 14 | 1.814 | 20.995 | 0.825 |
| 3/4 | 14 | 1.814 | 26.441 | 1.041 |
| 1 | 11 | 2.309 | 33.249 | 1.309 |
| 1 1/4 | 11 | 2.309 | 49.910 | 1.65 |
| 1 1/2 | 11 | 2.309 | 47.803 | 1.882 |
| 2 | 11 | 2.309 | 59.614 | 2.347 |
| 2 1/2 | 11 | 2.309 | 75.184 | 2.96 |
| 3 | 11 | 2.309 | 87.884 | 3.46 |
| 4 | 11 | 2.309 | 113.03 | 4.45 |
| NPT THREAD SIZES | ||||
|---|---|---|---|---|
| Thread Size [inches] |
Threads Per Inch |
Pitch [Inches] |
Major Diameter Of The Thread | |
| mm | inches | |||
| 1/8 | 27 | 0.03704 | 10.29 | 0.405 |
| 1/4 | 18 | 0.05556 | 13.72 | 0.540 |
| 3/8 | 18 | 0.05556 | 17.15 | 0.675 |
| 1/2 | 14 | 0.07143 | 21.34 | 0.840 |
| 3/4 | 14 | 0.07143 | 26.67 | 1.050 |
| 1 | 11 1/2 | 0.08696 | 33.40 | 1.315 |
| 1 1/4 | 11 1/2 | 0.08696 | 42.16 | 1.660 |
| 1 1/2 | 11 1/2 | 0.08696 | 48.26 | 1.900 |
| 2 | 11 1/2 | 0.08696 | 60.33 | 2.375 |
| 2 1/2 | 8 | 0.125 | 73.03 | 2.875 |
| 3 | 8 | 0.125 | 88.90 | 3.500 |
| 4 | 8 | 0.125 | 114.30 | 4.500 |