Stud Finder
What we checked on LG G6 and Redmi Note 13 Pro 5G
In our hands-on checks, both an LG G6 and a Xiaomi Redmi Note 13 Pro 5G found screws through drywall and wood at reported depths of approximately 1–2 cm. These are observations from our development checks, not a rated maximum depth or a guarantee for every phone, screw or wall.
| Phone | Materials checked | Reported depth | Observed result |
|---|---|---|---|
| LG G6 | Drywall and wood | Approximately 1–2 cm | Screws found in these checks |
| Xiaomi Redmi Note 13 Pro 5G | Drywall and wood | Approximately 1–2 cm | Screws found in these checks |
We do not yet have a published trial-by-trial log for these material checks. Screw dimensions, the exact depth reference, repeat counts, missed detections and location error are not documented here. We therefore do not assign a detection percentage or millimetre accuracy to either phone. The detected target was the screw, not the wood itself.
Locate the sensor before scanning
We have added a feature that helps identify the magnetometer's location within the phone. It helps the user position the sensing area for a scan. This is separate from checking whether a magnetometer is present. We have not published a controlled before-and-after measurement of the feature's effect on location accuracy, so we do not attach a percentage improvement to it.
Simulation, recorded signals and material checks answer different questions
- Simulated sweeps, July 28–August 3, 2026: a simplified magnetic model generated signals for a screw at a known location and depth. Automated tests checked detection, estimated centre and response to noise. On August 3 we used the model to tune smoothing after simplifying the detection engine. The development summary reports that the earlier setting lost more than half the simulated signal on a fast sweep. That result concerns the model, not a measured improvement across real walls.
- LG G6 recordings, August 3: three physical recordings captured rotation away from metal, sweeps over a screw and a screw held near the sensor then removed. They exposed false signals and background-tracking errors. These recordings were made without a wall.
- LG G6 and Xiaomi material checks: the drywall and wood observations above are a separate set of checks. They are not the source of the numbers in the LG G6 replay report.
Read the detailed case study, why our stud finder app showed false signals on an LG G6, for the recorded failure, the changes and the remaining limits.
What the phone measures
A magnetometer measures magnetic flux density along three axes. Android reports magnetic field sensor values in microteslas (µT), and apps can check whether the device has the sensor.[1] A nearby steel object may change those readings. The sensor does not provide an image of the wall or a direct measurement of wood.
For a phone setup checklist, see whether your phone can be used as a stud finder. For the signal calculation, see how three-axis readings are combined.
How to interpret the pattern
Scroll the table sideways on a small screen.
| Observation | Possible explanation | Next check |
|---|---|---|
| A local response repeats in the same spot | A nearby steel fastener or another metal object | Repeat the pass and compare above and below |
| Several separate responses align vertically | A line of fasteners attached to framing | Verify the framing before choosing a mounting point |
| A broad response covers a large area | Metal lath, steel framing, pipework, or interference | Check accessories and wall construction; do not assume wood framing |
| No repeatable response | Missing sensor, deep fasteners, unsuitable wall, or no fastener near the scan | Check hardware and use another detection method |
Why results differ between phones and walls
The sensor's position in the handset, its distance from the fastener, nearby magnetic accessories, and the wall construction all affect a reading. A phone case that contains a magnet can overwhelm the smaller response you are looking for. Keep the phone's orientation consistent and follow the app's calibration prompts.
A number such as 60 or 90 µT is not a universal stud threshold. What matters is a repeatable local change compared with the surrounding area. A graph or beep does not identify which object caused that change.
Where magnetic detection has limits
Steel pipes, conduit, and corner bead can be confused with fasteners. Wood, plastic pipes, and the presence of live voltage cannot be identified reliably by this method. A continuous magnetic band is a reason to investigate the wall, not proof of a specific framing material.
Plaster over wood lath and plaster over wire mesh behave differently. Fasteners under thick plaster may be too far away for a useful phone reading, while metal mesh can create broad interference. See the plaster-wall guide and the tool comparison.
What would demonstrate that an app works on your wall?
A useful check compares repeated readings with a fastener or framing position that can be verified independently. Record the phone model, wall material, case condition, and whether the same position is detected from both directions. Do not treat an unknown wall as its own ground truth.
This article combines our reported hands-on checks with a separate sensor-replay case study. Neither establishes a controlled accuracy rate across phones or wall types. Detection alone does not certify a mounting point; follow the hardware manufacturer's requirements and verify the wall before drilling.