Bubble Level
Lay your phone down to see the tilt
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A bubble level that uses the tilt sensor in your phone to check whether a floor, a shelf or a picture frame is level. It shows the tilt in degrees to 0.1° and the slope in percent.
How to use
- Open this page on a phone. On devices that ask for permission, such as an iPhone, press "Start the level" and allow access.
- To check a flat surface, lay the phone on it. A round bubble appears together with "Left–right tilt", "Front–back tilt" and "Slope".
- To check a wall or the edge of a frame, stand the phone on one of its edges against it. The display changes to a bar-shaped bubble.
- If a camera bump makes the reading wrong, press "Set current position as 0" on a flat surface. Press "Clear zero" to undo it.
How it works
- When the tilt is within 0.3°, the page shows "Level" and changes color.
- Slope in percent is tan(angle) × 100. An angle of 1° is about 1.7 %, and 45° is 100 %.
- The sensor readings are smoothed to reduce jitter. The screen stays on while the level runs, and the zero you set is saved in this browser on this device.
- On a computer without a tilt sensor, the page shows a QR code that opens it on a phone.
Questions and answers
- How accurate is a phone level app?
- It depends on the sensor in your device. It is fine for setting furniture or hanging a picture, but precise building work needs a real spirit level.
- How many degrees is a 1% slope?
- About 0.57°. A 1 % slope rises 1 cm over 1 m. For small angles, 1° is about a 1.7 % slope.
- Why does the level not move on my iPhone?
- Press "Start the level" and allow motion and orientation access. If you declined, allow it for this site in the browser settings and press the button again.