When you're working on a construction project, selecting the correct screw size is crucial. Choosing the wrong one could split the wood, damage the material or affect the structural integrity of your project.

That's why it's important to understand the three basic screw measurements: gauge, length and threads per inch. Then, when referring to plans, instructions or specs, you'll be able to make sense of all those numbers that appear on the packaging.

For instance, if the label reads 6-32 x 1 1/2", this indicates that the screw has a diameter of 6/64 inches and 32 threads per inch (more than double the standard thread count for that type of screw). The shaft length is in inches, which helps you figure out where to drive the screw.

Most fasteners come with different heads — flat, Phillips or hex — and lengths that are designed for specific projects or materials. Knowing the right screws to choose will help you complete your project more quickly and easily.

While the number of threads on a screw is an easy measurement, understanding the meaning of the other two dimensions can be confusing. For example, the first number listed on a package is often called the screw gauge and refers to the diameter of the screw head, also known as the major diameter. Screws have a variety of gauges, from #2 through #16. The gauge number corresponds to a fraction of an inch, which you can easily match up using a screw gauge chart or decimal equivalent calculator.

The second number is the threads per inch, which refers to the spacing between the screw's thread peaks in an inch-long section of the screw. You can measure the threads on a screw with a thread gauge, which consists of strips of metal with different sizes of thread cut into them. To find the threads per inch on a screw, simply hold the thread gauge near the screw and count how many threads are visible in an inch-long strip of the screw.

Screws are sized by driver type, length, shank diameter and threads per inch to ensure that you're working with the best possible fastener for each job. By familiarizing yourself with these measurements, you'll be able to choose the right screws for a variety of tasks from woodworking to installing drywall and even a metal roof.

Knowing the basics of screw sizes will ensure that you're using the best fastener for the job. Keep in mind that you should always select a screw that's approximately half the thickness of the material it's going into. If you go much longer, you may risk damaging the opposite side of the material and if you're too short, the screw won't anchor properly. Keep these tips in mind and you'll be a pro when it comes to screw selection. Good luck!metric to standard