Lead
On 21 December 2025 The Guardian published a practical guide showing 25 unexpected, everyday uses for modern smartphones. The piece demonstrates how built-in sensors and widely available apps turn a handset into tools for measuring, detecting, translating, documenting and even rudimentary health screening. Examples range from Apple’s AR-based Measure app and lidar 3D scans to magnetometer-based metal detection and phone-as-webcam setups. The take-home: with little or no extra kit, a phone can replace many single-purpose gadgets for home, travel and light professional tasks.
Key takeaways
- Apple’s Measure app uses augmented reality and the camera to estimate distances and heights, including a person’s height, on iPhone models with relevant sensors.
- Many phones include a magnetometer; consumer apps can repurpose it for basic metal-detection tasks, useful for casual beachcombing though less accurate than dedicated detectors.
- Several Android handsets still ship with infrared blasters or can control devices over Wi‑Fi/Bluetooth; paired remote apps let phones operate TVs, set‑top boxes and air conditioners.
- Apps such as FilmBox (iOS/Android) can convert photographic negatives into digital images; scanned photos can then be refined with common editing tools.
- iOS 26 introduces Hold Assist, which notifies the caller when a live human voice is detected on the other end of a line, sparing users long on‑hold waits.
- Lidar and similar depth sensors on recent phones allow users to create 3D scans for printing, gaming assets or documenting items for insurance and resale.
- Offline mapping plus GPS enables safe navigation and route logging in areas without mobile reception when maps are downloaded in advance.
- Cheap NFC stickers (often under £10 for a pack of ~50 online) can trigger routines — turn on Wi‑Fi, set Do Not Disturb, start playlists — without installing a hub.
Background
Smartphones have steadily absorbed functions once handled by standalone gadgets by packing multiple sensors and powerful processors into pocketable designs. Accelerometers, gyroscopes, magnetometers, depth sensors and high‑quality cameras were originally intended for navigation, photography and system stability; developers now exploit them for a broad array of utility apps. The app ecosystem — with both platform vendors and third‑party developers — has accelerated this trend by providing easy-to-install software that taps hardware capabilities previously reserved for specialist devices.
Users and professionals alike have embraced these multipurpose workflows because they reduce cost and encourage portability. That said, consumer smartphone solutions frequently trade off precision for convenience: they are excellent for quick checks, documentation and hobbyist use, but not always substitutes for calibrated professional instruments. The expanding set of health‑related apps also raises questions about validation, regulation and safe interpretation of readings drawn from consumer sensors.
Main event
AR measuring tools: Apple’s Measure app and comparable Android tools combine camera data and motion sensors to approximate distances, ceiling heights and object dimensions. On phones with depth sensors, these tools are faster than pulling out a tape measure for routine home tasks, and some workflows let you capture a person’s height for quick comparisons without marking walls.
Metal detection and magnetometer hacks: A phone’s magnetometer, intended to improve navigation, can detect local disturbances in magnetic fields. Several lightweight apps present that information as an onscreen signal; they will not match the range or selectivity of a purpose-built metal detector but are adequate for locating small, buried metallic items during casual outings.
Remote control, scanning and conversion: Many Android devices include infrared transmitters or pair with smart devices over Bluetooth/Wi‑Fi to act as universal remotes. Film‑negative scanning apps like FilmBox convert negatives into editable digital files when the negatives are backlit, and document‑scan functions built into many camera apps let users capture contract pages and receipts as shareable PDFs.
Health and environmental sensing: Research dating from 2022 tested whether a smartphone microphone could capture heart sounds; follow‑up commercial tools for cardiac screening exist in some markets. Phones and connected smartwatches also estimate blood oxygen saturation and can log trends. Decibel‑meter apps give reasonably accurate sound‑level readings suitable for documenting nuisance noise but should not replace calibrated professional instruments when legal precision is required.
Productivity and creative uses: Phones can serve as higher‑quality webcams (via Handoff on iPhone/Mac or Link to Windows on Android/Windows), remote slide controllers for PowerPoint/Keynote, lightweight podcast studios with an inexpensive external mic, and practical helpers like colour‑matching apps for repainting, plant‑ID services, live translation (e.g., Google Translate) and shared shopping lists (Bring!, AnyList, Listonic).
Analysis & implications
Democratization of tools: The broad availability of sensors and apps means tasks that once demanded specialist gear are now accessible to many more people. This lowers barriers for hobbyists, small businesses and renters who need fast documentation — for example, 3D scans for insurance records or quick room measurements when planning renovations. The convenience effect is substantial: users report saving time and avoiding small purchases simply by using smartphone-based solutions.
Accuracy limits and responsible use: Most smartphone workarounds are optimized for convenience rather than metrological accuracy. That matters in safety‑critical or legally consequential contexts — such as formal noise disputes, clinical diagnostics, or professional surveying — where calibrated instruments and certified practitioners remain essential. The growing number of health apps increases the risk of false reassurance or unnecessary anxiety, so clear disclaimers and pathways to professional care are necessary.
Privacy and data flows: Many of these apps involve image, audio or location data that may be uploaded to cloud services for processing. Users should review permissions, storage policies and sharing settings; for sensitive uses (medical screening, property inventories) consider local processing options or trusted providers with clear data‑handling policies. Regulators and platform owners will likely increase scrutiny of health and safety applications as adoption grows.
Market and product trends: Expect closer integration between phone manufacturers and third‑party developers to deliver more polished, validated utilities — for example, improved depth sensing, better on‑device ML for object recognition, and expanded SDKs for secure medical‑grade data capture. Accessory makers will continue offering inexpensive hardware that augments smartphone capabilities (external mics, clip‑on lenses, calibrated colorimeters) to bridge the gap between convenience and professional performance.
Comparison & data
| Function | Best suited phone feature | Practical accuracy/notes |
|---|---|---|
| AR measuring | Camera + motion sensors (+ lidar on some models) | Good for room dims; ± a few centimetres for typical uses |
| Metal detection | Magnetometer | Can find small metal items nearby; range and selectivity limited |
| 3D scanning | Lidar/depth sensor | Creates printable models; fine detail depends on sensor quality |
| Decibel logging | Microphone + calibrated app | Reasonable for complaints; not a legal substitute for certified meters |
The table sets practical expectations: smartphone tools are reliable for informal, everyday tasks but often fall short where professional calibration or certification is required. Users should treat phone-derived data as a first pass that can guide action, not as definitive evidence in high‑stakes situations.
Reactions & quotes
Vendors and researchers have both highlighted the possibilities and the caveats of repurposing phone sensors.
“You can use AR tools on iPhone to estimate room dimensions and a person’s height for quick measurements.”
Apple (product support/feature notes)
The Guardian guide and related trials underline that mobile microphones and processing can record heart sounds well enough for screening studies, while emphasising they are no replacement for clinical auscultation.
“Mobile technologies are a viable way of recording heart sounds,”
2022 trial summary (academic research)
Unconfirmed
- Exact sensitivity and detection range for magnetometer-based metal‑detecting apps vary widely; specific performance claims from some apps lack third‑party validation.
- Details about the availability, regulatory clearance and marketed indications of commercial ‘cardiac screening’ apps in the US may differ by vendor and are not universally equivalent to clinical devices.
- Some platforms’ promises about on‑device processing for privacy vary between app versions and regions; users should verify the current privacy policy before assuming offline operation.
Bottom line
Modern smartphones already provide many reliable, low‑cost substitutes for single‑purpose gadgets, making everyday tasks faster and often cheaper. From measuring a wall to digitising negatives or recording decibel levels, these tools expand what a single pocket device can do — particularly for hobbyists, renters and small businesses that need quick documentation.
However, users should match the tool to the task: phone apps are excellent for convenience and documentation but not always suitable where precision, legal admissibility or clinical accuracy matter. Reviewing permissions, understanding limits, and turning to trained professionals when readings suggest risk will maximise the practical benefits while reducing potential harms.