How to Select Wood Screws

Updated April 17, 2017

If you work with wood, you must know what type of wood screw to use for your projects. Wood screws come with a variety of heads and threads. Knowing what type of wood screw to use might seem like an easy task, but they come in such a wide variety that you might find it daunting to make a selection. If you pick the wrong screw, your project could literally fall apart. Once you learn how to pick a wood screw, your projects will piece together--and stay together.

Match the screw's length to the depth of the wood. For instance, the screw must successfully hold together two pieces of wood. To do this, it must fully penetrate the first piece of wood and reach at least 3/4 of the way into the adjoining piece of wood. Too short screws might pull loose. Too long screws might protrude from the adjoining wood.

Match the screw's diameter to the depth of the wood. For instance, manufacturers rate wood screw thickness according to a scale of 1 to 20. A #1 screw measures .06 inches across. A #20 measures .38 inches across. A #10 measures .19 inches in diameter. If the wood is really thick, a relatively thin 4 or 6 screw might work. If the wood is really narrow, a fatter screw of 15 to 18 will hold the wood better.

Select the head to match your tools. For instance, screws come in Philips or Flat heads. Philips heads have a cross-shaped notch that fits a cross-shaped (Philips) screwdriver. Flat heads have a single notch that fit a flat screwdriver.

Match the head type to the desired finish. Screws come in three types of heads: flat, round, and oval. Flat heads consist of a smooth head that fits flush with the wood. Round heads consist of a rounded head that sits raised above the wood. Oval heads consist of an oval head that raises higher than a flat head but not as high as a round head. Consider whether your project requires a smooth finish or if you want a screw head protruding slightly from the wood.

Match the scew's notch to your screwdriver's width. For instance, screwdrivers typically consist of hardened stainless steel. Screws typically consist of soft metals like brass or metal alloy. If the hardened screwdriver fits too loosely, you could strip the head of the screw and ruin the screw. Ruining a screw in mid-turn can strip the hole in the wood.


  • If you choose a flat head screw, you can countersink it into the wood. Counter sinking the screw consists of drilling a slight hole into the wood then sinking the screw head past the surface of the wood. You can then fill this hole with wood putty or some other filler.
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About the Author

Randal Thomas has been completing woodworking, gardening and DIY projects for over a quarter-century. A writer of career-related articles since 2003, Thomas received his Bachelor of Science from the University of Central Missouri. He has over 10 years in printing and publishing and is currently working on several independent writing projects.