Stud Finder: Metal Detector X

Find wall studs with the sensor already in your iPhone — no $30 gadget, no subscription, no gimmicks.

Stud Finder – Wall Scanner uses your iPhone's built-in magnetometer to detect the metal screws and nails that fasten drywall to every stud. Slide your phone across the wall, watch the gauge, mark the spot, hang your shelf.

PAY ONCE, OR DON'T PAY AT ALL
• Scanning, calibration, the tutorial and the bubble level are free forever.
• Pro is a single $3.99 one-time purchase — no subscription, no weekly trial that quietly renews, no credit-card trap. Most "free" stud finder apps charge $5–10 per week. We think that's absurd.
• A hardware stud finder costs $20–50 and lives in a drawer. Your phone is already in your pocket.

HONEST ABOUT HOW IT WORKS
This app detects the SCREWS, not the wood. Wood isn't magnetic — but the drywall screws holding the wall to each stud are, and they line up vertically along every stud. That's the trick, and we say so up front:
• No fake radar screens, no pretend "wall X-ray".
• A built-in guide confirms a real stud line: after one hit, it walks you through checking ~12 in (30 cm) above and below. Three hits in a vertical line = a stud, not a stray nail.
• Clear limits, stated in the app: works best on drywall over wood studs; metal studs read differently; concrete and very deep screws are hard; MagSafe cases must come off. Always confirm with a small test nail before drilling — the app itself reminds you.

BUILT LIKE AN INSTRUMENT
• Live analog gauge with gray / amber / red zones, tuned needle damping and a rolling waveform of the last 6 seconds.
• Guided 2-second calibration zeroes the sensor on every wall, with automatic warning when a magnet (or MagSafe case) is skewing readings.
• Rising beep + haptics as you approach a stud — usable without looking at the screen.
• A LEARN-IT-ONCE tutorial teaches the technique in 60 seconds: slide slow, confirm with three points, calibrate on a blank spot. Replay it anytime.

MARK, MEASURE, HANG
• Tap MARK on a hit to pin it on a per-wall ruler. Free includes 3 marks on one wall — try the whole flow before paying anything.
• Drag pins to tape-measured positions; the app checks the spacing against the 16″/24″ US framing standards and tells you honestly which gaps are confirmed and which are still estimates.
• Everything is stored on your phone only. No account, no cloud, readings never leave the device.

ADS THAT KNOW THEIR PLACE
The free tier shows one small banner at the bottom of the scan screen. That's it. Ads never interrupt scanning, never go full-screen, never appear on the level, marks or settings screens. Pro removes them entirely.

STUD FINDER PRO — $3.99 ONCE, YOURS FOREVER
• Remove all ads
• Unlimited walls & marks
• Metal detector mode — find pipes, conduit and lost nails with the same sensor
• High sensitivity — for deep screws and plaster walls

ALSO IN THE BOX
• Bubble level (free): bull's-eye + edge level with Set Zero calibration — hang it straight, not just on a stud.
• Works offline. Portrait-optimized, one-handed use.

REQUIRES
An iPhone with a magnetometer (all modern iPhones). The app is honest if your device can't scan — it will tell you instead of showing fake readings.

Find the stud. Skip the subscription.