Bubble Level
Turn your phone into a digital spirit level using the built-in tilt sensor. The bubble responds in real time and turns green when the surface is balanced. No app required.
Place your phone flat on a surface to check if it is level.
Requires a mobile device with a built-in tilt sensor.
Bubble Level turns your phone into a digital spirit level using the device's built-in tilt sensor. Place your phone on any surface, watch the bubble respond in real time, and get a clear LEVEL confirmation the moment the reading falls within ±1.5° of perfectly flat — no separate app or hardware required.
How to Use
Tap Start Level and place your phone flat on the surface you want to check. The bubble in the circular vial moves in real time based on the device's tilt angle. When both the left-right and front-back angles drop below ±1.5°, the bubble turns green and the LEVEL badge appears. The angle readouts beneath the vial give precise degree values for both axes.
On iOS devices (Safari), the browser will ask for permission to access the motion sensor — tap Allow when prompted. On Android and most other mobile browsers, the sensor activates immediately after tapping Start.
Reading the Vial
The circular display mirrors the behavior of a physical spirit level. The bubble moves toward the high side of the surface:
- When the right edge is higher than the left, the bubble shifts right
- When the front of the device is higher, the bubble shifts forward
The two angle readouts show the precise tilt in degrees. Both values need to be close to zero for a confirmed level reading.
What Can You Check?
This tool works for any horizontal surface check — shelves, tables, countertops, picture frames, appliances, and furniture. To check a vertical surface (such as a wall), hold the back of the phone flat against it and note when the bubble centers.
Privacy
This tool reads only from the browser's DeviceOrientation API — a local hardware interface that never transmits data over the network. No orientation readings, usage data, or device information are sent to any server.
FAQ
Does this work on a desktop computer?
No. Desktop PCs and laptops do not have the accelerometers this tool depends on. Open it on a smartphone or tablet for full functionality.
Why does Safari on iPhone ask for permission?
iOS 13 and later requires explicit user permission before a website can read motion sensor data. Tapping Allow grants access for the current session only — you can revoke it at any time in Safari settings.
How accurate is the reading?
Accuracy depends on your device's accelerometer quality. Most modern smartphones are accurate to within ±0.5–1°, which is more than adequate for everyday tasks like hanging pictures or leveling furniture. For professional construction work, a dedicated hardware level is recommended.
What does the dashed ring inside the vial represent?
The dashed circle marks the target zone. When the bubble sits inside it, the device is close to level. When the bubble turns green and the LEVEL badge appears, the reading has passed the ±1.5° threshold.
Can I check if a wall is vertical?
Yes. Hold the back of your phone flush against the wall surface and watch the angle readouts. When both values approach zero, the wall is plumb.
Does the tool drain battery?
The tool uses requestAnimationFrame for animation and the lightweight DeviceOrientation API — both are very low power. Battery impact during normal use is minimal.