#5-40 UNC Thread Specs
Standard: ASME B1.1 (UNC)
Find the technical dimensions, threads per inch (TPI), and tapping guidelines for the #5-40 UNC unified thread.
Compliant with the ASME B1.1 standard, this size has a nominal major diameter of 0.125 inches (3.18 mm) with a pitch of 0.025 inches (TPI of 40).
For general engineering or fastening, the standard recommended tap drill is 0.1 inches (2.54 mm) to achieve adequate thread engagement.
Dimensional Specifications (Inches & mm)
Size Designation
#5-40 UNC
Major Diameter (Nominal)
0.125 in(3.18 mm)
TPI (Threads per Inch)
40
Pitch
0.025 in
Pitch Diameter
0.1088 in(2.76 mm)
Minor Diameter (Ext)
0.0979 in(2.49 mm)
Minor Diameter (Int)
0.1006 in(2.56 mm)
Thread Height
0.0217 in
Drilling & Strength Specs
Tap Drill Size
0.1 in(2.54 mm)
Stress Area
0.008 in²(5.13 mm²)
Quick Unit Converter
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Frequently Asked Questions
What is the tap drill size for #5-40 UNC?
The recommended tap drill size for a #5-40 UNC thread is 0.1 inches (approx. 2.54 mm) to achieve standard thread engagement.
How many threads per inch (TPI) does a #5-40 UNC bolt have?
A standard #5-40 UNC thread has exactly 40 threads per inch (TPI), with a corresponding linear pitch of 0.025 inches.
What is the major diameter of a #5-40 UNC thread in millimeters?
The nominal major diameter of a #5-40 UNC thread is 0.125 inches, which converts to 3.18 mm.