Try a smartphone stud finder app

Download a stud finder app that uses your phone's built-in magnetometer to detect steel fasteners behind drywall. Hold the phone flat against the wall and sweep slowly — the app displays spikes in magnetic field strength when passing over screws or nails.

Why It Works

Most modern smartphones contain a magnetometer (compass sensor) that can detect changes in magnetic fields caused by steel drywall fasteners. The app visualizes these readings as a graph or indicator.

Tips

• Remove your phone case, especially if it has a magnetic closure or metal plate
• Calibrate the app first by waving your phone in a figure-8 pattern
• A $3 rare earth magnet will significantly outperform any phone app — use apps only as a last resort
• Results are inconsistent and phone sensors vary widely between models
• Popular free apps include Stud Finder (iOS) and Stud Detector (Android)