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UN Thread Calculator (Imperial / Inches)
UNC, UNF, UNEF & UNS Thread Pitch and Diameter Calculator
This free thread calculator is an imperial thread calculator for UN threads in inches. Use it as a UN thread calculator for UNC, UNF, UNEF and UNS sizes to get thread pitch (TPI) and key diameters. It’s also a quick thread pitch calculator when you know the TPI and need major/minor/pitch diameter values. This page is a fast, lookup-table based calculator designed for machinists, engineers, and designers working with Unified Inch screw threads.
Inputs
Results
External thread callout
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Internal thread callout
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| Basic (ASME B1.1) |
|---|
| No | --- |
Series | --- |
| TPI | --- |
Lead angle | --- |
| d — basic major diameter | --- |
H — fundamental triangle height | --- |
| d2 — basic pitch diameter | --- |
d1 — basic minor diameter | --- |
| d3 — basic minor (root) diameter | --- |
es — fundamental deviation (external) | --- |
| External (bolt) limits |
|---|
| d max — major diameter | --- |
d min — major diameter | --- |
| d2 max — pitch diameter | --- |
d2 min — pitch diameter | --- |
| d1 max — minor diameter | --- |
d3 max — minor (root) diameter | --- |
| Internal (nut) limits |
|---|
| D2 max — pitch diameter | --- |
D2 min — pitch diameter | --- |
| D1 max — minor diameter | --- |
D1 min — minor diameter | --- |
| D min — major diameter | --- |
Classes | --- |
About ASME Unified Inch Threads
Unified Inch threads (UN) are defined by the ASME B1.1 standard and commonly used across North America and in
global manufacturing where inch fasteners are specified. This calculator focuses on external and internal UN
thread sizes and uses lookup data to match common designation formats (for example, 1/4-20 UNC or 10-32 UNF).
Common Searches and Examples
People often search for specific sizes like 3/16 UNF thread, 7/16 UNF thread, or dimension lookups such as 3/4-16 UNF thread dimensions.
Use the filter box to quickly find a designation (for example, 3/16-24 UNF, 7/16-20 UNF, or 3/4-16 UNF) and calculate major, minor, and pitch diameter values.
What This Thread Dimension Calculator Outputs
This screw thread calculator reports basic UN geometry and limit sizes for external thread calculator (bolt) and internal thread calculator (nut) conditions.
It’s useful as a thread minor diameter calculator, a pitch diameter calculator, and a threads per inch calculator helper when you need fast inch-thread dimensions.
FAQ
What is a UN thread?
UN (Unified Inch) threads are inch-based screw threads with standard series such as UNC (coarse),
UNF (fine), UNEF (extra fine) and UNS (special). Engineers typically reference them by nominal diameter and
threads-per-inch (TPI).
UNC vs UNF — what’s the difference?
UNC is a coarse series (fewer threads per inch) and UNF is a fine series (more threads per inch). The thread
series changes TPI and therefore changes the resulting thread geometry and diameters.
Is this a thread calculator in inches?
Yes. This is an imperial thread calculator inches tool. Inputs and outputs are based on inch
thread designations and inch dimensions.
Does it support UNS?
Yes — where present in the lookup data, you can select UNS thread calculator sizes from the
dropdown and compute dimensions the same way.
What this UN thread calculator does
This tool is designed for quick lookups when you need thread dimensions in inches: major diameter, minor diameter, pitch diameter, and tolerance limits for internal (nut/tapped hole) and external (bolt/screw) threads. It covers common series such as UNC, UNF, UNEF and UNS per ASME B1.1.
Popular searches
Use this page as a thread pitch (TPI) calculator, thread minor diameter calculator, and pitch diameter calculator for unified inch screw threads.
Charts and reference