#5 screw dimensions and bolt sizes are commonly used for specialized industrial equipment, aerospace components, and precision mechanical fastening. This size is standardized with a 0.125″ nominal major diameter and is available in #5-40 coarse (UNC) or #5-44 fine (UNF), representing 40 and 44 threads per inch (TPI) respectively. This reference chart follows ANSI/ASME B18.6.3 and B18.3 standards for the head size and ANSI/ASME B1.1 standards for the thread dimensions to ensure compatibility across imperial fastening applications.
Disclaimer: Dimensions and tolerances may vary slightly depending on head style, manufacturer, or material — always verify with the official product datasheet before use.
#5-40 UNC Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
0.1191
0.1242
Pitch Diameter
0.1054
0.108
Minor Diameter
Not specified
0.0944
Threads Per Inch (TPI)
40
Major Diameter
0.1199
0.125
Pitch Diameter
0.1069
0.1088
Minor Diameter
Not specified
0.0952
Threads Per Inch (TPI)
40
#5-44 UNF Screw & Bolt – ANSI/ASME B1.1
Dimension
Size (in)
Min
Max
Major Diameter
0.1195
0.1243
Pitch Diameter
0.107
0.1095
Minor Diameter
Not specified
0.0972
Threads Per Inch (TPI)
44
Major Diameter
0.1202
0.125
Pitch Diameter
0.1083
0.1102
Minor Diameter
Not specified
0.0979
Threads Per Inch (TPI)
44
Major Diameter –
The largest diameter of the external thread, measured crest to crest.
This defines the nominal size of the screw or bolt.
Pitch Diameter –
The diameter of an imaginary cylinder where the thread thickness equals
the space between threads. This dimension primarily controls thread fit
and tolerance class of 2A and 3A.
Minor Diameter –
The smallest diameter of the external thread, measured root to root.
This affects thread strength and clearance.
Threads Per Inch (TPI) –
The number of complete threads within one inch of thread length.
Higher TPI values indicate a finer thread pitch.
What is the tap drill size for #5-40 and #5-44 screws or bolts?
On aluminum, brass, and plastics material the recommended tap drill for #5-40 coarse thread is a #38 drill bit (0.1020″). For the #5-44 fine thread, the recommended tap drill is a #37 drill bit (0.1040″). While on steel, stainless, and iron material 7/64 (0.1090”) drill usually used for #5-40 and #35 (0.1100”) drill for #5-44.
What clearance hole size is needed for a #5 bolt or screw?
For a Close Fit, a #30 drill (0.1290″) is recommended. For a Normal/Free Fit (standard clearance), a #29 drill (0.1360″) usually be used.
What is the equivalent size for #5 in metric?
For size #5, the nearest metric match is M3.
This particular size has a maximum major diameter of 2.981 mm (0.11736 inch),
which means the measurement offset is only about 0.194 mm (0.00764 inch).
While these diameters are nearly identical, metric and imperial fasteners are not interchangeable. They utilize fundamentally different thread systems: Imperial fasteners are measured by Threads Per Inch (TPI), whereas metric fasteners use Thread Pitch. Mixing metric and imperial hardware is strongly discouraged, as it can lead to damaged components, reduced load-bearing capacity, and catastrophic mechanical failure.
What is the difference between a bolt and a screw?
The difference is based on the intent of the fastener’s use; If the primary intent is for the fastener to pass through an unthreaded holes and be assembled with a nut, it is a Bolt. In this application, you usually hold the head and turn the nut to apply tension. But if the primary intent is for the fastener to be installed into a threaded (tapped) hole, it is a Screw. In this application, the connection is tightened by turning the head of the fastener itself.
