1"-12 UNF Thread Specs
Standard: ASME B1.1 (UNF)
Find the technical dimensions, threads per inch (TPI), and tapping guidelines for the 1"-12 UNF unified thread.
Compliant with the ASME B1.1 standard, this size has a nominal major diameter of 1 inches (25.4 mm) with a pitch of 0.08333 inches (TPI of 12).
For general engineering or fastening, the standard recommended tap drill is 0.9167 inches (23.28 mm) to achieve adequate thread engagement.
Dimensional Specifications (Inches & mm)
Size Designation
1"-12 UNF
Major Diameter (Nominal)
1 in(25.4 mm)
TPI (Threads per Inch)
12
Pitch
0.08333 in
Pitch Diameter
0.9459 in(24.03 mm)
Minor Diameter (Ext)
0.9098 in(23.11 mm)
Minor Diameter (Int)
0.9188 in(23.34 mm)
Thread Height
0.0722 in
Drilling & Strength Specs
Tap Drill Size
0.9167 in(23.28 mm)
Stress Area
0.663 in²(427.77 mm²)
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Frequently Asked Questions
What is the tap drill size for 1"-12 UNF?
The recommended tap drill size for a 1"-12 UNF thread is 0.9167 inches (approx. 23.28 mm) to achieve standard thread engagement.
How many threads per inch (TPI) does a 1"-12 UNF bolt have?
A standard 1"-12 UNF thread has exactly 12 threads per inch (TPI), with a corresponding linear pitch of 0.08333 inches.
What is the major diameter of a 1"-12 UNF thread in millimeters?
The nominal major diameter of a 1"-12 UNF thread is 1 inches, which converts to 25.4 mm.