Stud finders are highly accurate, but their reliability depends heavily on using them correctly and choosing the right type for your specific wall material. Inaccurate readings are usually caused by user error or the device being tricked by dense materials like plaster and lath.
Yes, stud finders can absolutely be wrong. Because they primarily detect changes in wall density rather than the wood itself, they are highly prone to "false positives" or missing the stud entirely.
Yes, your phone can function as a stud finder, but with a catch: it uses your phone's built-in magnetometer (which powers the compass) to detect the metal screws or nails hidden in your drywall, rather than the wood itself.
Quick Look
As demonstrated on Ask This Old House, studs are typically spaced 16 inches on center in older homes and 24 inches on center in some newer construction.
If it calibrates over the stud, it will be ignoring anything of that density, so it will ignore the stud. Letting other objects get near the stud finder once it's been calibrated. Even a pencil, or finger will throw it off so keep your digits well away until you stop moving it and need to mark the wall.
Lath and plaster walls fell out of standard residential construction between the 1940s and 1960s. While traditional three-coat plaster was the go-to method for centuries, a massive post-WWII housing boom popularized drywall (Sheetrock), which was significantly cheaper and faster to install.
The "best" stud finder depends on your specific needs, but the Franklin Sensors ProSensor M210 is widely regarded as the best overall electronic model. It uses a 13-sensor array that requires no manual calibration and instantly shows the exact width of a stud across a row of glowing LEDs.
Conventional stud finders rely on a small number of sensors, typically just one or two, to detect changes in density behind the wall. Franklin Sensors changed this up with patented technology, including 3-13 sensors and a wide, horizontal design. More sensors mean more reference points across the wall.
Studs run vertically behind the drywall in your home or apartment. Knocking, using magnets, and flashlights are a few ways to help you locate a stud without a stud finder.
The iPhone does not have a built-in stud-finder tool. However, you can download a metal detector app from the App Store. These apps use the iPhone’s built-in magnetometer (compass) to detect the metal screws or nails used to attach drywall to the wooden studs.
Studs in most homes are spaced 16 or 24 inches apart on center, meaning the distance from the center of one stud to the next. Interior walls are usually 16" OC, while garages, basements, and exterior walls may use 24" OC for energy efficiency.
Pipes, electrical wires, and ductwork can create interference during the stud-finding process. These obstacles often run through walls and can throw off readings from stud finders.
Metal studs aren’t widely used in houses primarily because wood is cheaper, faster to install, and easier for residential trades to work with. While metal doesn't burn or rot, it requires specialized tools, creates thermal bridging issues, and offers less flexibility for hanging heavy household items.
Even if you know how to use a stud finder and are doing it correctly, the devices may not be as effective for plaster walls. Because plaster walls are thicker, harder and more brittle than drywall, finding a stud can be a bigger challenge.
The best cheap stud finders fall into two categories: high-powered magnets and budget electronic sensors. Both options provide excellent accuracy without the premium price tag.
Stud finders often struggle on exterior walls because insulation, thick sheathing, siding layers, and wall depth interfere with sensor readings. These materials weaken or scatter the signal that electronic stud finders rely on.
Drywall Anchor Types for Lighter Items
Plastic ribbed anchors are the most commonly used anchors for lighter items and can hold up to 10 pounds per pair. Threaded drywall anchors are suitable for objects weighing up to 25 pounds and are ideal for use on drywall.
Professionals typically rely on multi-sensor electronic scanners and high-powered magnetic locators for speed and accuracy. They prioritize tools that don't require manual calibration and provide exact visual readings of stud centers and edges.
The best stud finders available at The Home Depot depend on the job, but the overall top-rated choices are the Franklin Sensors ProSensor M90 for quick DIY jobs, and the Franklin Sensors ProSensor M210 for heavy-duty projects and maximum accuracy.
Some drywall finishers add a small amount of dish soap (like Dawn) to drywall mud as a workability hack. They do this to act as a surfactant, which reduces the surface tension of the mud.
In the UK, drywall is primarily referred to as plasterboard.