Stud Finder & Metal Detector
Utilities · ★ 4.3 · 359 ratings
Find studs and metal behind walls with your iPhone
The app reads the magnetometer already in your phone and watches for the small distortions that nails, screws and brackets create in the magnetic field — so you can locate a stud before you drill, without buying a separate tool.
Free · iOS 14.0 or later · 11MB · English
Screenshots
More screens · tap to enlarge
What it does
Finds what is actually there
Nails, screws, brackets and the ferrous fixings that hold a stud in place — behind drywall, plaster, plywood, OSB and wood.
Four ways to read it
A bar meter, a radial field visualisation, a gauge with min/avg/max, and a history graph plotted over time. Different walls make different views easier to read.
See, hear and feel the hit
Visual, audio and haptic indicators fire together, so you can keep your eyes on the wall and your hand on the pencil instead of on the screen.
Real numbers, not just a bar
The absolute field strength in microtesla, plus how it is changing and the minimum, average and maximum of the current run — enough to tell a stud from a stray screw.
Tune the sensitivity
A slider adjusts how aggressively the app reacts, which matters when a wall is thick or when the fixings are small and deep.
No extra tool to buy or charge
Everything runs on the magnetometer already in your phone. Nothing to pack, nothing to keep batteries for.
How it works
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1
Take the case off
If your case has magnets or metal parts — MagSafe included — remove it first, or it will swamp the reading.
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2
Sweep the wall slowly
Move the phone flat and steadily across the surface. The reading rises as you pass over a ferrous object and falls again as you move away.
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3
Mark the peak
The highest reading is the object. Sweep across it from both directions and mark the middle to find the centre of the stud.
Questions
How does a phone find studs without a dedicated tool? +
It does not sense wood directly. It uses the magnetometer to detect the ferrous metal that holds the stud in place — the nails and screws fixing drywall to the frame — and those follow the studs, which is why locating them locates the stud.
Will it find a stud that has no nails or screws in it? +
No. Anything non-ferrous is invisible to a magnetometer: bare timber with no fixings, copper pipe, aluminium and plastic conduit will not register. This is a limitation of the physics, not of the app.
Do I need to take my phone case off? +
If it contains magnets or metal, yes — MagSafe cases especially. A magnet a few millimetres from the sensor completely overwhelms a wall fixing several centimetres away.
How do I find where the sensor is in my phone? +
Move a small screw slowly across the back of the phone while watching the absolute field value. The position where the number peaks is where the magnetometer sits. Keeping that spot against the wall gives you the strongest, most repeatable readings.
What do the microtesla numbers mean? +
They are the absolute strength of the magnetic field at the sensor. The Earth's field alone gives a background reading, so what matters is not the absolute figure but how sharply it rises as you pass over an object — which is why the app also shows the minimum, average and maximum of your sweep.
Does it work through plaster and tile? +
It works through drywall, plaster, plywood, OSB and wood. Greater depth means a weaker signal, so thick plaster or a tiled surface will reduce sensitivity, and raising the sensitivity slider helps.
Is Stud Finder free? +
The app is free to download from the App Store. Some capabilities are unlocked through an in-app purchase; the current terms are always shown inside the app before you buy.
Know where the stud is before you drill
Free on the App Store, uses the sensor already in your phone, and there is nothing extra to carry.
