Side-by-Side Comparison
Imperial Threads (UNC/UNF)
#4-40 UNC vs. #8-32 UNC
Comparing 2 standards across 8 specifications. 8 key differences identified.
Comparing:
#4-40 UNC
#8-32 UNC
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).
8-32 UNC is a numbered Unified Coarse machine screw thread with a major diameter of 0.1640 inches (4.166 mm) and 32 threads per inch (TPI). Requiring a #29 (0.1360 inch) tap drill, it is the standard fastener for North American electrical ceiling junction boxes, light fixtures, and kitchen cabinet hardware knobs.
Specification Comparison Table
8 Parameters| Parameter / Spec | ||
|---|---|---|
|
Nominal Major Diameter
|
0.1120 in (2.845 mm) | 0.1640 in (4.166 mm) |
|
Threads Per Inch (TPI)
|
40 TPI (Coarse pitch: 0.635 mm) | 32 TPI (Coarse pitch: 0.794 mm) |
|
Fine Pitch Equivalent
|
#4-48 UNF (0.529 mm pitch) | #8-36 UNF (0.706 mm pitch) |
|
Recommended Tap Drill Size
|
#43 drill bit (0.0890 in / 2.26 mm) | #29 drill bit (0.1360 in / 3.45 mm) |
|
Minor Diameter (Internal)
|
0.0849 in (2.156 mm) | 0.1302 in (3.307 mm) |
|
Tensile Stress Area
|
0.00604 in² (3.90 mm²) | 0.0140 in² (9.03 mm²) |
|
Common Computing Role
|
D-sub / VGA / DVI thumbscrew standoffs | — |
|
Common Drive Size
|
— | PH2 / Slotted / Square #2 |