Stud Finder
Find studs in your wall with your phone.
Your phone already has the sensor — no extra hardware to buy. Stud Finder uses the built-in magnetometer to detect the metal screws and nails inside each stud. Take off your case, hold it flat to the drywall, and slide it across the wall.
Scan to install on your phone
Point your Android camera at the code.
Stud Finder: key facts
Stud Finder is an Android app that uses the phone's built-in magnetometer to locate the steel screws and nails driven into wood wall studs behind drywall. It detects ferrous metal, not wood, and it does not work on plaster-and-lath or metal-stud walls.
- Platform
- Android only. There is no iPhone version. The app is distributed through the Google Play Store.
- Sensor
- The app samples magnetic flux density at 50 Hz to detect ferrous anomalies — steel screws and nails.
- Device compatibility
- Approximately 14% of Android devices lack a magnetometer. The app checks your sensor for free before any purchase and blocks the subscription if it is missing.
- What it detects
- Steel drywall fasteners only. It cannot detect wood directly, live AC wires, plastic pipes, or hidden cameras.
- Wall types
- Works on drywall over wood studs, up to about 5/8" board. It fails on plaster over wire lath and on metal studs.
- Typical stud spacing
- Wood-framed walls are usually framed 16 inches on center, sometimes 24 inches on center.
- Price
- $4.99 per week with a 3-day free trial, or $39.99 per year. Cancel anytime in Google Play.
- Positioning
- The honest stud finder — built like a real tool, not a gimmick app, and explicit about what it cannot do.
How to Find a Stud with Your Phone
Follow these 4 simple steps to detect studs correctly using magnetic signals.
Take off your case
Magnetic inserts, MagSafe rings, metal plates, or folio clasps block the sensor. Remove your case entirely before scanning.
Hold the phone flat
Keep the back of your phone flat against the drywall to position the magnetometer as close to the screws as possible.
Move slowly
Slide the phone side-to-side at a slow walk. Moving too quickly will cause you to overshoot the narrow magnetic field spike.
Watch the signal
When the readings spike, a steel screw or nail is right under the sensor. Mark the spot—the wood stud is directly behind it.
The Physics: Phone compasses rely on an internal chip called a magnetometer. When this sensor passes over a ferromagnetic steel nail or drywall screw, it measures a tiny localized disturbance in the earth's magnetic field — a ferrous anomaly. Stud Finder samples magnetic flux density at 50 Hz, roughly fifty readings per second, which is fast enough to catch that spike while you slide the phone across the wall at walking speed. Because drywall screws are driven into the center of a wood stud, mapping a vertical line of anomalies pinpoints the stud. For the underlying science, see Britannica's explanation of magnetometer physics.
Stud Finder App vs. Magnetic vs. Electronic Stud Finders
There are three ways to find a stud. Two of them detect metal fasteners; only one reads the wood itself. Here is the honest comparison.
| Feature | Stud Finder App (phone magnetometer) | Magnetic Stud Finder | Electronic Stud Finder |
|---|---|---|---|
| What it detects | Steel screws and nails in the stud, via magnetic field changes | Steel screws and nails, via magnetic attraction | Density changes in the wall, via capacitive plates — reads the wood itself |
| Extra hardware | None. Uses the Android phone you already own | A separate magnet tool to buy and carry | A separate battery-powered device to buy and carry |
| Power | Runs on the phone's battery | None — a passive magnet, nothing to charge | Requires a battery, and drifts when the battery is low |
| Finds stud edges | No. It marks fastener positions, which sit at the stud center | No. It marks fastener positions only | Yes. It reports both edges, so it can estimate stud width |
| Plaster and lath walls | Unreliable. Wire lath produces constant magnetic interference | Sometimes works by finding individual lath nails | Usually fails. Plaster is too thick and too uneven in density |
| Metal studs | No. A metal stud reads as magnetic along its entire length | Detects the stud, but cannot isolate fasteners | Yes, and most models have a dedicated metal-scan mode |
| Common failure mode | A magnetic phone case, or drywall glued on with no screws near scan height | Missing a stud entirely between widely spaced fasteners | False positives from pipes, foil-faced insulation, and vapor barriers |
| Always with you | Yes. It is on the phone in your pocket | Only if you remembered the toolbox | Only if you remembered the toolbox |
| Best for | Hanging shelves, mirrors, art, and TV mounts on drywall | Quick checks with zero setup and nothing to fail | Framing, remodels, and any job that needs true stud width |
Scroll the table sideways to see all three tools.
The Verdict: For hanging a shelf, picture frame, or TV mount on drywall over wood studs, a phone magnetometer app finds the stud safely and costs nothing extra. If you are framing, remodeling, or need the exact width and edges of a stud, buy an electronic stud finder.
What Stud Finder Can & Can't Do
We build tools, not magic tricks. Understanding these limitations is critical for a safe, successful project.
Works Well On
- Standard Drywall: Perfect for standard sheetrock walls up to 5/8" thickness.
- Drywall Fasteners: Locates steel drywall screws and nails driven into studs.
- Wood Stud Centers: Pinpoints the exact horizontal position of the vertical studs where screws are anchored.
Struggles With
- Plaster & Lath Walls: Thick plaster layers over wire mesh lath create magnetic shielding that blocks the sensor.
- Metal Studs: Metal studs create a continuous magnetic reading across the entire wall, preventing fastener isolation.
- Fastener-Free Walls: If installers glued the drywall and used zero screws near your scan height, no signal will register.
We Never Claim To Find
- Live AC Wires
- Plastic PVC Pipes
- Direct Wood Density
- Millimeter Depth Readings
- Hidden Cameras
DIY Guides & How-Tos
Real answers to the questions homeowners ask Google, Gemini, ChatGPT, and Claude. Every guide is written to give you the direct answer first.
Do Stud Finder Apps Really Work? The Science Behind Phone Sensors
Yes, stud finder apps work by using your phone's built-in magnetometer to detect metal screws and nails inside walls — no extra hardware required.
Read Guide → How-ToHow to Find a Stud to Hang a Heavy Mirror Safely
Locate structural studs by sliding a stud finder horizontally, marking spikes, and verifying the stud center before drilling. Always anchor into at least one stud.
Read Guide → LimitationsHow to Find Studs in Plaster and Lath Walls (Without Damaging Your Home)
Electronic stud finders fail on plaster. The most reliable method is a strong magnet or phone app to locate the lath nails securing the plaster to the studs behind.
Read Guide → ComparisonMagnetic vs. Electronic Stud Finders: Which Is Best for Your Project?
Magnetic finders detect nails with no batteries. Electronic finders sense wall density changes but produce false positives. Each has a distinct use case.
Read Guide → IdentificationHow to Tell If You Have Wood or Metal Studs Inside Your Walls
Metal studs trigger a continuous magnetic pull along their full length. Wood studs produce discrete spikes every 8–12 inches where screws are driven in.
Read Guide → How-ToHow to Find a Ceiling Joist Without a Stud Finder: 5 Easy Methods
Use the knock test, measure from an edge wall at 16- or 24-inch intervals, look for nail pops, or run a magnet along the ceiling to locate drywall screws.
Read Guide → SafetyHow to Mount a TV on Drywall Without Studs: Safe & Secure Methods
Toggle bolts and snap toggles can hold TVs under 50–70 lbs. For heavier sets or articulating mounts, you must anchor into actual studs to prevent collapse.
Read Guide → Getting StartedCan a Phone Be Used as a Stud Finder? Yes — Here's How It Works
Any Android phone with a magnetometer can find studs by detecting the steel screws in the wall. Learn which phones are compatible and how to check for free.
Read Guide → TechnologyThe Technology Behind Stud Finder Apps: How Magnetometer Sensors Work
Phone apps read 3-axis magnetic flux density data from your phone's MEMS magnetometer chip to detect ferromagnetic anomalies caused by steel fasteners.
Read Guide → How-ToHow to Find a Stud Without a Stud Finder: 6 Household Hacks
Tap the wall to listen for solid sound, measure 16 inches from a corner, check near outlet boxes, or look for subtle nail pops in the drywall finish.
Read Guide → SafetyHow to Avoid Drilling Into Electrical Wires and Pipes When Hanging Shelves
Keep drill holes at least 1.25 inches from stud edges, avoid areas above or below switches, and use a non-contact voltage detector before drilling.
Read Guide → TroubleshootingWhy Your Stud Finder Isn't Working on Exterior Walls (and How to Fix It)
Foil-faced insulation and vapor barriers disrupt electronic stud finders. Switch to a magnetic app that detects drywall screws directly, bypassing insulation interference.
Read Guide → How-ToHow to Find Studs to Hang Floating Shelves (Step-by-Step DIY Guide)
Locate two stud centers, align the bracket, pre-drill, and secure with heavy-duty wood screws. Floating shelves must hit studs to bear leverage weight safely.
Read Guide →Frequently Asked Questions
Common questions from DIYers who want to find studs reliably.
Do stud finder apps actually work?
Yes — stud finder apps work if they use the phone's magnetometer. The Stud Finder app detects the magnetic signature of the steel screws and nails that hold drywall to the studs. It does not see through walls and it does not measure wood density directly; it locates the metal fasteners that mark where the wood stud is.
How does the Stud Finder app find a stud?
The Stud Finder app finds a stud by sampling your phone's magnetometer at 50 Hz and watching for a localized spike in magnetic flux density. That spike is a ferrous anomaly — a steel drywall screw or nail. Because those fasteners are driven into the center of a wood stud, a vertical line of spikes marks the stud.
Why do I have to take my phone case off?
You have to take your phone case off because many cases contain magnets. A MagSafe ring, a metal plate for a car mount, or a folio clasp saturates the phone's magnetometer with interference, which hides the far smaller magnetic signature of a drywall screw. Scanning with a bare phone is the single biggest accuracy improvement you can make.
Does the app work on plaster or metal-stud walls?
No — the Stud Finder app does not work reliably on plaster-and-lath walls or on metal-stud walls. Plaster is usually backed by wire lath, which produces constant magnetic interference, and a metal stud is magnetic along its whole length, so the signal never resolves into individual fasteners. The app is built for drywall over wood studs.
How far apart are wall studs?
Wall studs in North American wood-framed homes are typically spaced 16 inches on center, and 24 inches on center in some newer or non-load-bearing walls. Once you have found one stud, measuring 16 or 24 inches horizontally predicts where the next one should be — then confirm it by scanning rather than assuming.
Is it accurate enough to hang a TV?
Yes — the Stud Finder app is accurate enough to hang a TV when it is used correctly. Drywall screws are driven into the center of a wood stud, so a vertical line of hits confirms the stud position. Always confirm two or three fasteners in a vertical line before drilling a heavy mount such as a television bracket.
What phones are supported?
Stud Finder supports any Android phone with a built-in magnetometer, the same sensor the compass app uses. Approximately 14% of Android devices ship without a magnetometer, so the app runs a free compatibility check on your device before you scan or subscribe, and blocks the purchase if the sensor is missing.
Does Stud Finder work on iPhone?
No — Stud Finder is an Android-only app and is not available for iPhone or iPad. It is distributed exclusively through the Google Play Store.
Can the app detect live electrical wires or pipes?
No — the Stud Finder app cannot detect live electrical wires, plastic PVC pipes, or hidden cameras, and it never claims to. It responds only to ferrous metal. Before drilling, use a non-contact voltage tester and avoid the area directly above or below outlets and switches, where cable runs vertically inside the stud bay.
How much does Stud Finder cost?
Stud Finder costs $4.99 per week with a 3-day free trial, or $39.99 per year. There are no hidden fees and no locked feature tiers, and you can cancel at any time from your Google Play account settings.
Is there a free version or trial?
Yes — Stud Finder includes a fully functional 3-day free trial on the weekly plan. The trial lets you confirm the app works on your wall and finish a hanging project, and you are not charged if you cancel before it ends. Checking whether your phone has a magnetometer is always free and needs no subscription.
How is this different from a hardware stud finder?
The difference is what each tool measures. An electronic hardware stud finder measures changes in wall density with capacitive plates, so it can read the wood edge directly. Stud Finder reads the magnetic field of the steel fasteners driven into the stud. A dedicated tool is better for framing and new construction; the app is better when you want to hang something today without buying anything.
Ready to hang it safely?
No hardware store trips, no expensive scanner purchases. Use the tool that is already in your pocket.
Get Stud Finder on Google Play
On a desktop? Scan with your Android phone to install.