How does a Stud Finder Find Studs?

If you want to hang a picture, install a bookshelf or speaker shelf, put up a cabinet or suspend a wall mirror, you’ll likely want to test your drywall to find studs for maximum support. Some people use a small hammer to tap along the wall, listing for a change in tone to find studs. Others hold a bare lamp against the wall to look for telltale taping and nail heads covered by paint. But the easiest way to find studs is to use a stud finder.

There are two basic types of stud finders on the market that find studs using very different methods. A magnetic stud finder will find studs by reacting to the magnetic fields generated by steel nails in the stud board. An electronic stud finder finds studs by measuring wall density.

Magnetic stud finders are simple tools that contain a magnet. By passing the magnetic stud finder very slowly across the wall, you can verify the location of steel nails used to affix the drywall to studs. This type of stud finder is very inexpensive, but has drawbacks. You must move the stud finder slowly or it won’t have time to react before passing a nail head. The device also needs to move along the wall at a height that will take it directly over nail heads, or close to them. While contractors know approximately where nails should be located, many homeowners don’t. This can make using a magnetic stud finder a little challenging and time consuming.

The electronic stud finder measures electrostatic fields to find studs. Both drywall and supporting studs generate electrostatic fields, each with their own density signature. When an electronic stud finder passes over a stud, a circuit in the stud finder detects the change to the denser electrostatic field, and back again to the drywall signature. By measuring the span of change, the device can locate the center of the stud for you. Other models sound a tone or feature LED lights to let you know when you’ve passed each edge of the stud, allowing you to determine the stud’s center yourself.

Multiscanner stud finders not only find studs but will locate hidden pipes and wiring located behind drywall. This is handy for plumbing and electrical work, but also allows you to avoid driving nails into wires. This stud finder will also find metal studs.

Electronic and multiscanner stud finders range in price according to features, but can start as low as 10 US Dollars (USD) for a simple model, ranging up to 50 USD or more. Most basic models scan up to ¾ of an inch (19 mm) into the wall, but dual settings that allow “deep scanning” of up to three inches (76 mm) or more are also available. Stud finders can be found everywhere home improvement tools are sold.