Side-by-Side Comparison
Imperial Threads (UNC/UNF)
1/2"-13 UNC vs. #8-32 UNC
Comparing 2 standards across 7 specifications. 7 key differences identified.
Comparing:
1/2"-13 UNC
#8-32 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.
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
7 Parameters| Parameter / Spec | ||
|---|---|---|
|
Nominal Major Diameter
|
0.5000 in (12.700 mm) | 0.1640 in (4.166 mm) |
|
Threads Per Inch (TPI)
|
13 TPI (Coarse pitch: 1.954 mm) | 32 TPI (Coarse pitch: 0.794 mm) |
|
Fine Pitch Equivalent
|
1/2"-20 UNF (1.270 mm pitch — standard automotive wheel lugs) | #8-36 UNF (0.706 mm pitch) |
|
Recommended Tap Drill Size
|
27/64 in drill bit (0.4219 in / 10.72 mm) | #29 drill bit (0.1360 in / 3.45 mm) |
|
Minor Diameter (Internal)
|
0.4167 in (10.584 mm) | 0.1302 in (3.307 mm) |
|
Tensile Stress Area
|
0.1419 in² (91.5 mm²) | 0.0140 in² (9.03 mm²) |
|
Common Drive Size
|
3/4" Hex (19.05 mm) / 3/8" Allen | PH2 / Slotted / Square #2 |