NPT Thread Calculator / Pipe Thread Calculator [ Free ]

Yeah, I know, that “Free” on the end of that title looks a little cheezy, LOL.  What can I say, just trying to get the word out about an important feature in our G-Wizard Calculator.  Believe it or not, it isn’t the NPT Thread Calculator that’s important, although it’s cool.  It’s that we’re going to be offering all of the Quick Reference and Geometry applets in G-Wizard for free.  All you have to do is sign up for the 30-day trial and you can access them free, for life, including all the updates and customer service.

Pretty cool, eh?

And no, I haven’t lost my mind, the heart of G-Wizard is still Feeds and Speeds and that isn’t free (sorry!), but it pays for itself in no time through savings in time and tool life.

Now what about that Pipe Thread Calculator?

It's pretty cool.  It lives on the Threads tab, and you select the Tapered subtab.  NPT and Pipe Threads in general are typically tapered threads.  National Standard Taper Pipe is the full name for this thread.

Here's what it looks like:

To use it, select the Thread Size and the rest will follow.  As you can see the diagram covers external thread and internal thread dimensions.  You get all the following npt thread dimensions:

• Overall Length (L4)
• Effective Length (L2)
• Nominal Diameter (L5)
• 2P (2 pitches)
• L3
• Hand tight engagement length (L1)
• Taper Angle / Lead Angle
• E0 Pitch Diameter
• Pipe Outer Diameter
• E3 Pitch Diameter
• E2 Pitch diameter
• Pitch
• E5 Pitch Diameter
• TPI (Threads Per Inch)
• Min Flat at Crest
• Max Flat at Crest
• E1 Pitch Diameter
• Height

That gives a very complete description of the npt thread dimensions, sufficient to cut such npt threads via thread milling, single point threading, or any method you choose.  There's even a guide to selecting tap drills.  And, you can specify units for inch length or metric units.

Calculations for these external and internal npt pipe dimensions are all based on the ansi same b1.20.1 standard as stated right on the diagram.

G-Wizard Thread Calculator: Premium Version

You get all that for free just for trialing G-Wizard Calculator.  But, there's more available in the form of our premium G-Wizard Thread Calculator.  You can see some of its additional features here, again with the combined external thread and internal thread views:

With the Premium version you get:

• Many more thread families, such as the BSPT British tapered pipe threads.
• The Report page which lists all the data values and also allows you to save them as a CSV file that you can print:

And there's much more.