A #12 screw has a major diameter of 0.216 inches (7/32").
Understanding Screw Gauge Sizes
In the United States, smaller screw diameters are typically designated by a gauge number rather than a direct measurement in inches. This numerical system provides a standardized way to specify the major diameter of the screw's threads. Generally, the larger the gauge number, the larger the screw's diameter.
For example, a #12 screw is significantly larger in diameter than a #6 or #8 screw. This gauge system is commonly used for various types of fasteners, including wood screws, machine screws, and tapping screws.
Common US Screw Size Conversions
To help visualize the #12 screw size in context with other common diameters, refer to the following conversion table which lists their corresponding decimal and fractional inch equivalents:
| Screw Size | Inch Decimal | Nearest Fraction |
|---|---|---|
| #6 | 0.138 in. | 9/64" |
| #8 | 0.164 in. | 5/32" |
| #10 | 0.190 in. | 3/16" |
| #12 | 0.216 in. | 7/32" |
Source: US Fastener Sizes and Conversion Charts
Practical Applications and Measurement
Accurate sizing is crucial when selecting fasteners for any project. Knowing both the decimal (0.216") and fractional (7/32") equivalent of a #12 screw helps ensure compatibility with pre-drilled holes, nuts, or mating components.
- Clearance Holes: For a #12 screw to pass through a material freely, a drill bit slightly larger than its major diameter, such as a 7/32" (0.21875") or even a 1/4" (0.250") drill bit, would typically be used.
- Pilot Holes: When fastening into wood or other materials where the screw threads need to grip, a smaller pilot hole is drilled to prevent splitting and ease insertion. The specific pilot hole size depends on the material type and screw length.
Understanding these size conversions is essential across various fields, including construction, furniture assembly, and electronics, ensuring secure and proper fastening.
