Getting Started with G-Wizard Thread Calculator

G-Wizard Thread Calculator is a premium add-on module for G-Wizard Calculator.  You must have a working version of G-Wizard Calculator to use G-Wizard Thread Calculator.

Note:  G-Wizard Thread Calculator is currently in Beta Test and is therefore not officially released for production use.
You’re welcome to use it for free during the Beta Test.  Be sure to check all values carefully for errors and
report any problems or feedback to

What is a Thread Calculator?

Screw Threads are complex beasts.  They’re based on standards that run to hundreds of pages.  We depend on screw threads to be interchangeable if we follow the proper standard correctly.  The goal of a Thread Calculator is to give you comprehensive capabilities to deal with threads:

  • Determine Thread Dimensions such as Major Diameter, Minor Diameter, Pitch Diameter, and dozens of other variables that specify a thread.
  • How to check those dimensions, for example use the “Measure Over Wires” technique or what the dimensions should be if you want to make Go/No Go Gages.
  • Tell  you what the tolerances are to keep your threads within spec.
  • Calculate all of this for standard and non-standard sizes.
  • Tell you what tap drills to use for tapping internal threads.
  • Print detailed reports to be used for inspection, quality control, and documentation.
  • Handle the largest possible variety of thread types.

G-Wizard Thread Calculator can do all this and more.

A Quick Tour of G-Wizard Thread Calculator

Using G-Wizard Thread Calculator is straightforward.  Follow these steps:

Select the GW Threads tab in G-Wizard Calculator

If there is no GW Threads tab, it means you’re not registered to use GW Thread Calculator.  Go to the product page and register for a free trial or purchase.

Select Straight or Tapered (Pipe) Threads

GW Thread Calculator divides threads into Straight and Tapered (Pipe threads are often tapered) groups.  Select the tab at top for the one you want.

Select a Thread Family and Preferred Size

Threads belong to families that determine the general shape and geometry of the threads.  A Family also has a list of Preferred Thread Sizes that are standard for that Family.  You select both using the dropdowns at the top left of the GW Thread Calculator:

Custom Threads

Not all families allows custom thread sizes, but many do.  You’ll need to enter a Nominal Size (also known as the Basic Major Diameter) and either TPI (Threads Per Inch) or Pitch (many metric Families use pitch) for your custom size.  GW Thread Calculator will then calculate all the dimensions for the thread.

Tolerance Classes

Not all thread families have tolerance classes, but when they do, you’ll set them here from the “Class” dropdown.

Thread Starts

Change the number of starts from the default of “1” to create a multi-start thread.

Tapping Drills

Determine the optimal size for your tapping drill based on whether you have a cutting or forming (thread rolling) tap and on what percentage threads you want to create.  Be sure to check out our in-depth article to understand the effect of thread percentages on tap life.

Graphics View vs Report View

Graphics View gives you a quick visual summary of the thread.  Report View has a lot more information and is intended when you want to print a report with as much information as possible about a particular thread.

CADCAM Thread Wizard

Click this button to load the currently selected thread into CADCAM Wizards.

Measurement Over Wires

G-Wizard Thread Calculator includes a Measurement Over Wires Calculator for External Thread measurement:

At the top of the MOW Calculator are the Min, Max, and Recommended Best Size to use for measuring wires.  Enter your actual wire size, and the MOW Min and Max for the thread to be in spec are given.  Enter the Size Over Wires you measure and the pitch diameter of the thread will be given.

Thread Families Supported by G-Wizard Thread Calculator

Thread Family



Free Thread Families included with G-WIzard
808 Sizes

 Unified National: UN, UNC, UNF, UNEF, UNS  ANSI/ASME B1.1-2003  371

GW Thread Calculator allows Custom diameter and TPI

 ISO Metric M, Coarse and Fine  ASME B1.13-2005


 GW Thread Calculator allows Custom diameter and TPI

Premium Thread Families added by G-Wizard Thread Calculator

 UNM – Miniature Thread Sizes for Watchmaking and similar applications  ASME B1.10  14
 UN STI – Screw Thread inserts such as Helicoil.  UNC and UNF sizes.  ASME B18.29.1-2010  43
 ISO STI – Screw Thread inserts such as Helicoil.  Coarse and Fine sizes.  ASME B1.13M-2005  44
 Pg (Panzergewinde) Conduit Threads  DIN 40430  10
 UNJ – Aerospace Thread.  UNJC, UNJF, and UNJEF Sizes  SAE AS8879-D  82

Plus Custom diameter and TPI combinations

Metric MJ – Aerospace Thread.  B1.21M-1997 157
Plus Custom diameter and Pitch combinations
British Standard Whitworth (BSW) British Standard Whitworth (BSW) 19
Plus Custom diameter and TPI combinations
British Standard Whitworth Fine (BSF) British Standard Whitworth (BSW) 16
Plus Custom diameter and TPI combinations
 British Association (BA) BS 93:2008  17