If you’re working with screws, you know the diameter is a crucial measurement. Choosing the right screw for your project ensures it can fit into whatever material you’re using, and helps prevent it from coming loose or breaking in the future. But did you know there are actually four different diameter measurements when describing a screw? Understanding these measurements can help you measure your screw with more precision and ensure the correct one is selected for your next project.
The first measurement you’ll see is the screw gauge, also known as the major diameter. Screws with a major diameter less than a quarter inch are usually labeled from #0 to #12, while those that have a larger diameter are typically labeled in fractions of an inch. The diameter of a screw is measured along the crest, or peak, of its threads.
Once you’ve determined the screw’s gauge, you can start to determine its shaft length. This is important because a long screw won’t reach the bottom of your material, while a short screw won’t hold as well. This is especially important when it comes to drywall and other types of lightweight materials.
While you can use a ruler or tape measure to get the length of a screw, calipers offer more precision for measuring screw dimensions. Calipers can be used to measure not just the diameter and length of a screw, but also its thread pitch, which is the distance between each individual thread. #8 screw diameter
