Magnetometer: Stud Finder

Magnetometer is a metal detector and stud finder that uses your phone's built-in magnetic sensor to find iron and steel behind walls, under floors and inside furniture, and to measure the magnetic field in µT, mT or Gauss.

★ What it detects
Ferrous metal only: screws and nails in studs and joists, steel pipes, rebar, brackets, hinges and door strikes, within a few centimetres of the phone. Sweep slowly with the phone against the surface.

★ What it cannot detect
Gold, silver, copper, aluminium, wood and plastic are not magnetic, so no phone sensor can find them. It is not a coin finder and it does not trace copper wiring.

★ Calibrates as you turn the phone
The phone's own magnets create a large offset in the sensor. The app learns it while you turn the phone, so tilting alone does not look like metal. A progress bar on the meter shows the calibration; when it is full the reading goes live and the phone gives a short vibration. Zero here starts it again at any spot.

★ Meter modes
• Auto: radial gauge of the field deviation
• Earth Field: total field with a latitude band
• Metal Detector: deviation with an intensity verdict and optional vibration pulses that speed up near metal

★ Scanner and Stud Finder
Slide the phone flat along a wall: the Stud Finder marks the strongest point, where the screws and nails that hold the board to the stud are. The metal scanner shows the live deviation while you sweep.

★ Compass
Magnetic north or true north with declination.

★ Data and history
• Live X / Y / Z chart, min, average, max and peak
• Sensitivity 0.5x to 2.0x
• Saved readings with 7-day trend, favourites and side-by-side comparison
• One-second continuous log with CSV export
• Share a reading as an image, optional GPS tag
• Statistics report unlocked for 24 hours with a short rewarded ad

For DIY and renovation, checking for rebar and pipes before you drill, and physics experiments with magnets.

Recent changes:
Compass: “True N” derives Declination from approximate location and the built-in WMM 2025 model. A usable fix up to 10 minutes old is reused; otherwise one new approximate fix is requested, with about 12 seconds to wait. If location or model data is unusable: “True north unavailable — allow location access and try again.” Magnetic N remains available. Returning from another app no longer restarts a background heading service.