Pipe thread size finder tool

What is it?

A simple tool to find the size of the standard BSPP or BSPT (British Standard Pipe Parallel and Taper) pipe thread.

What for?

If you are using a metric system and looking for the correct size of the threaded connector / flexible tube during plumping, you are obviously measure the inner/outer diameter of the thread. It is easy, imperial system, one inch is 25,4mm, then a 1/2" connector should be around 12,7mm, right? Then you measure the connector, with a caliper, it shows 13,4mm, and you are happy, because you found it at first try it is definitely 1/2". Then you go to a shop and ask for a a 1/2" connector. You are still happy until you try it at home and it does not fit, it is so much bigger than it should be…

Then you start Googling for standards and you find these values for diameters:

• 1/8"= 10 mm outer thread; 8,2 mm inner thread
• 1/4"= 13,5 mm outer thread; 11,1 mm inner thread
• 3/8" = 17 mm outer thread; 14,6 mm inner thread
• 1/2"= 21,2 mm outer thread; 18,3 mm inner thread
• 3/4"= 26,7 mm outer thread; 23,8 mm inner thread
• 1"= 33,5 mm outer thread; 30 mm inner thread

What the heck? Who can memorize these values?

Now you do not have to, just print this simple tool and let this to tell you what size you need.

How to use it?

There are holes and extrusions on it, each pair has a mark on it. If you are facing with an outer thread just put it into the hole, which fits the best. If you have an inner thread put the tool's extrusion into it.

You do not have to worry about the inaccuracy of your printer or print settings, the tool has loose fit.