Side-by-Side Comparison
Imperial Threads (UNC/UNF)
3/8"-16 UNC vs. #4-40 UNC
Comparing 2 standards across 8 specifications. 8 key differences identified.
Comparing:
3/8"-16 UNC
#4-40 UNC
3/8"-16 UNC is a fractional Unified Coarse machine screw thread with a major diameter of 0.3750 inches (9.525 mm) and 16 threads per inch (TPI). Requiring a 5/16 inch (0.3125 inch) tap drill, it is the international standard for professional photography tripod-to-head mounting studs, cinema camera baseplates, and stage microphone stands.
4-40 UNC is a numbered Unified Coarse machine screw thread with a major diameter of 0.1120 inches (2.845 mm) and 40 threads per inch (TPI). Requiring a #43 (0.0890 inch) tap drill, it is the worldwide computing standard for D-subminiature connector jackscrews (VGA, DVI, RS-232 serial ports).
Specification Comparison Table
8 Parameters| Parameter / Spec | ||
|---|---|---|
|
Nominal Major Diameter
|
0.3750 in (9.525 mm) | 0.1120 in (2.845 mm) |
|
Threads Per Inch (TPI)
|
16 TPI (Coarse pitch: 1.588 mm) | 40 TPI (Coarse pitch: 0.635 mm) |
|
Fine Pitch Equivalent
|
3/8"-24 UNF (1.058 mm pitch) | #4-48 UNF (0.529 mm pitch) |
|
Recommended Tap Drill Size
|
5/16 in drill bit (0.3125 in / 7.94 mm) | #43 drill bit (0.0890 in / 2.26 mm) |
|
Minor Diameter (Internal)
|
0.3073 in (7.805 mm) | 0.0849 in (2.156 mm) |
|
Tensile Stress Area
|
0.0775 in² (50.0 mm²) | 0.00604 in² (3.90 mm²) |
|
Common Drive Size
|
9/16" Hex (14.28 mm) / 5/16" Allen | — |
|
Common Computing Role
|
— | D-sub / VGA / DVI thumbscrew standoffs |