BSP Threaded Fittings - Shop

Important Information - Please read the instructions at the bottom of this page on how BSP thread sizes are calculated 

Search the shop

Categories:

YOU CANNOT MEASURE A BSP THREAD WITH RULER/TAPE MEASURE

 
Assorted sizes BSPP Brass Bush 
If you have any questions regarding size issue please email and we will get back to you asap.

The threaded part(s) of plumbing fittings are made to a British Standard Pipe Thread size (BSP).  BSP sizes don’t match up with what you would measure using a ruler, which can obviously cause some confusion. For example a 3/4″ BSP thread actually measures more like 1" with a ruler.

A list of 16 thread sizes are defined by the standards, ranging from 1⁄16″ to 6″. The size was originally based on the inner diameter measured in inches of a steel tube for which the thread was intended. This often causes confusion, as people think the size refers to the outside diameter of the male thread.

Parallel (straight) threads, British Standard Pipe Parallel thread (BSPP)

The table below shows dimensions for male threads.

PHOTO IS FOR ILLUSTRATION PURPOSE ONLY

G / R
size		Thread
pitch		Major
diameter		Minor
diameter		Gauge
length		Tapping drill
R 95%G 80%
(in)(in−1)(mm)(in)(mm)(in)(mm)(in)(mm)(mm)(mm)
 1⁄16 28 0.907 0.3041 7.723 0.2583 6.561 5⁄32 4.0 6.6 6.8
 1⁄8 28 0.907 0.3830 9.728 0.3372 8.566 5⁄32 4.0 8.6 8.8
 1⁄4 19 1.337 0.5180 13.157 0.4506 11.445 .2367 6.0 11.5 11.8
 3⁄8 19 1.337 0.6560 16.662 0.5886 14.950 1⁄4 6.4 15.0 15.3
 1⁄2 14 1.814 0.8250 20.955 0.7335 18.631 .3214 8.2 18.7 19.1
 5⁄8 14 1.814 0.9020 22.911 0.8105 20.587 .3214 8.2 20.7 21.1
 3⁄4 14 1.814 1.0410 26.441 0.9495 24.117 3⁄8 9.5 24.2 24.6
 7⁄8 14 1.814 1.1890 30.201 1.0975 27.877 3⁄8 9.5 28.0 28.3
1 11 2.309 1.3090 33.249 1.1926 30.291 .4091 10.4 30.4 30.9
 1 1⁄8 11 2.309 1.4920 37.897 1.3756 34.939 .4091 10.4 35.1 35.5
 1 1⁄4 11 2.309 1.6500 41.910 1.5335 38.952 1⁄2 12.7 39.1 39.5
 1 3⁄8 11 2.309 1.7450 44.323 1.6285 41.365 1⁄2 12.7 41.5 42.0
 1 1⁄2 11 2.309 1.8820 47.803 1.7656 44.845 1⁄2 12.7 45.0 45.4
 1 5⁄8 11 2.309 2.0820 52.883 1.9656 49.926 5⁄8 15.9 50.1 50.5
 1 3⁄4 11 2.309 2.1160 53.746 1.9995 50.788 5⁄8 15.9 50.9 51.4
 1 7⁄8 11 2.309 2.2440 56.998 2.1276 54.041 5⁄8 15.9 54.2 54.6
2 11 2.309 2.3470 59.614 2.2306 56.656 5⁄8 15.9 56.8 57.2
 2 1⁄4 11 2.309 2.5870 65.710 2.4706 62.752 11⁄16 17.5 62.9 63.3
 2 1⁄2 11 2.309 2.9600 75.184 2.8435 72.226 11⁄16 17.5 72.4 72.8
 2 3⁄4 11 2.309 3.2100 81.534 3.0935 78.576 13⁄16 20.6 78.7 79.2
3 11 2.309 3.4600 87.884 3.3435 84.926 13⁄16 20.6 85.1 85.5
 3 1⁄4 11 2.309 3.7000 93.980 3.5835 91.022 7⁄8 22.2 91.2 91.6
 3 1⁄2 11 2.309 3.9500 100.330 3.8335 97.372 7⁄8 22.2 97.5 98.0
 3 3⁄4 11 2.309 4.2000 106.680 4.0835 103.722 7⁄8 22.2 103.9 104.3
4 11 2.309 4.4500 113.030 4.3335 110.072 1 25.4 110.2 110.7
 4 1⁄2 11 2.309 4.9500 125.730 4.8335 122.772 1 25.4 122.9 123.4
5 11 2.309 5.4500 138.430 5.3335 135.472 1 1⁄8 28.6 135.6 136.1
 5 1⁄2 11 2.309 5.9500 151.130 5.8335 148.172 1 1⁄8 28.6 148.3 148.8
6 11 2.309 6.4500 163.830 6.3335 160.872 1 1⁄8 28.6 161.0 161.5
7 10 2.540 7.4500 189.230 7.3220 185.979 1 3⁄8 34.9 186.1 186.6
8 10 2.540 8.4500 214.630 8.3220 211.379 1 1⁄2 38.1 211.5 212.0
9 10 2.540 9.4500 240.030 9.3220 236.779 1 1⁄2 38.1 236.9 237.4
10 10 2.540 10.4500 265.430 10.3220 262.179 1 5⁄8 41.3 262.3 262.8
11 8 3.175 11.4500 290.830 11.2900 286.766 1 5⁄8 41.3 287.0 287.6
12 8 3.175 12.4500 316.230 12.2900 312.166 1 5⁄8 41.3 312.4 313.0
13 8 3.175 13.6800 347.472 13.5200 343.408 1 5⁄8 41.3 343.6 344.2
14 8 3.175 14.6800 372.872 14.5200 368.808 1 3⁄4 44.5 369.0 369.6
15 8 3.175 15.6800 398.272 15.5200 394.208 1 3⁄4 44.5 394.4 395.0
16 8 3.175 16.6800 423.672 16.5200 419.608 1 7⁄8 47.6 419.8 420.4
17 8 3.175 17.6800 449.072 17.5200 445.008 2 50.8 445.2 445.8
18 8 3.175 18.6800 474.472 18.5200 470.408 2 50.8 470.6 471.2