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How to use Bubble Level
Press Start, then lay your phone flat on a surface or stand it on its long edge. The bubble centres when the surface is level.
- Open the page on a phone and press Start; allow motion access if asked.
- Lay the phone flat for the bullseye, or stand it on an edge for the vial.
- If your phone case is uneven, place it on a known level surface and tap “Set zero here”.
Formula & assumptions
- Readings come straight from your device’s sensors and stay on this device. Phone sensors are approximate; use a dedicated instrument where accuracy matters.
Questions
How accurate is a phone bubble level?
Typically within about 0.5° after calibration. Cases, camera bumps and dirty surfaces add error, so calibrate on a known level surface first.
Why does it need motion access?
The level reads the accelerometer, which measures gravity. On iPhone the browser asks for “Motion & Orientation” permission; nothing is sent anywhere.
Does it work on a laptop?
Most laptops and desktops have no accelerometer. Open the page on a phone or tablet.