Why the Same Surface Can Give Different Phone-Level Readings
You place a phone on a shelf, read the level, lift it, and put it back. The second number is slightly different. That can feel like the app changed its mind, but the phone may not be touching the surface in exactly the same way. A case edge, camera bump, speck of debris, orientation change, or calibration difference can alter the relationship between the device and the board. Bubble Level Tool provides horizontal and vertical measurement views, calibration, a visual bubble, and angle, percent, and mm/m units. Those features can help you compare positions, but they do not make a phone a certified professional instrument. Consistent setup is the key to getting readings that are useful for ordinary household checks. The phone measures its own orientation A level app reads the device’s sensors. It does not directly inspect the shelf. The app can only report the phone’s orientation while the phone is resting against a reference surface. If the device rocks or touches at different points...