3/8-16 Bolt Size and Thread Specifications
3/8-16 is a common imperial (UNC) bolt size for automotive, machinery, and structural use. A 3/8 inch nominal diameter with 16 threads per inch provides strong threads and is standard in many North American applications.
Specifications
| Specification | Value |
|---|---|
| Nominal diameter | 0.375 in (9.53 mm) |
| Threads per inch (TPI) | 16 |
| Tap drill size | 5/16 in |
| Closest metric equivalent | M10 |
Hex head size
| Bolt size | Hex head size |
|---|---|
| 3/8-16 | 9/16 in |
Common uses
3/8-16 bolts are used in automotive engines and chassis, machinery, and structural connections. They are a standard heavy-duty size and widely available.
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FAQ
What does 3/8-16 mean?
3/8 is the nominal diameter in inches (0.375 in). 16 is the number of threads per inch (TPI). It is a common UNC coarse thread.
What drill size for 3/8-16 tap?
Use a 5/16 in drill for a standard 3/8-16 tap.
What metric bolt is closest to 3/8-16?
M10 is the closest metric equivalent to 3/8-16. See M10 bolt size for full specs.