Magnetic stud finders catch on the fasteners that attach drywall to studs as you wave a magnet along the wall. ... Because these tools rely on the fastener actually being driven into the stud, ...

Magnetic stud finders catch on the fasteners that attach drywall to studs as you wave a magnet along the wall. ... The tool consistently found studs under drywall up to 3/4-inch thick in our testing.