Side-by-Side Comparison
Imperial Threads (UNC/UNF)
1/2"-13 UNC vs. #4-40 UNC
Comparing 2 standards across 8 specifications. 8 key differences identified.
Comparing:
1/2"-13 UNC
#4-40 UNC
1/2"-13 UNC is a heavy fractional Unified Coarse bolt thread with a major diameter of 0.5000 inches (12.700 mm) and 13 threads per inch (TPI). Requiring a 27/64 inch (0.4219 inch) tap drill, it is the standard structural fastener for automotive engine cradles, trailer hitches, and building timber connections.
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
|
0.5000 in (12.700 mm) | 0.1120 in (2.845 mm) |
|
Threads Per Inch (TPI)
|
13 TPI (Coarse pitch: 1.954 mm) | 40 TPI (Coarse pitch: 0.635 mm) |
|
Fine Pitch Equivalent
|
1/2"-20 UNF (1.270 mm pitch — standard automotive wheel lugs) | #4-48 UNF (0.529 mm pitch) |
|
Recommended Tap Drill Size
|
27/64 in drill bit (0.4219 in / 10.72 mm) | #43 drill bit (0.0890 in / 2.26 mm) |
|
Minor Diameter (Internal)
|
0.4167 in (10.584 mm) | 0.0849 in (2.156 mm) |
|
Tensile Stress Area
|
0.1419 in² (91.5 mm²) | 0.00604 in² (3.90 mm²) |
|
Common Drive Size
|
3/4" Hex (19.05 mm) / 3/8" Allen | — |
|
Common Computing Role
|
— | D-sub / VGA / DVI thumbscrew standoffs |