Choosing the right screw size is important for getting a tight grip on your fastening material. Using the wrong screw size can cause screws to break or bend and may not provide sufficient support for your fastening needs. There are several different dimensions to consider when measuring a screw, including its diameter and length. In order to properly measure a screw, you’ll need precise tooling such as calipers. These tools offer the highest level of accuracy and can help you get accurate measurements for even the most detailed screws.

Screw sizes are generally labeled with two numbers, the first of which is known as the gauge and designates the screw’s diameter. The number increases as the screw size goes up, and each increment corresponds to a fraction of an inch. For example, a #2 screw has a diameter of 0.0660″, while a #6 screw has a diameter of 0.076″. Engineering Toolbox also provides a handy chart that lists the gauges and their decimal equivalents for all imperial sizes up to #14.

The second number on a screw is its thread pitch, which refers to how many threads are placed along the length of the screw shaft. This measurement is important for determining the strength of the screw as well as how easily it will be installed into the substrate material. Screws with a higher thread pitch tend to have coarser threads than those with a lower thread count, and vice versa. screw diameters