Digital Bubble Level Online
A free digital bubble level that turns any smartphone into a precision measurement tool. Four measurement modes — 2D surface bubble, inclinometer, plumb line and camera AR overlay — cover everything from hanging a picture frame straight to checking the slope of a shelf or the vertical alignment of a wall.
How to Use
Load this page on a smartphone or tablet with an accelerometer. On desktop you'll see a QR code to scan with your phone camera.
Tap "Enable Sensors". On iOS 13+ a system prompt appears once — choose "Allow". Android grants access automatically.
Place the phone on a reference surface you trust to be flat, then long-press "Calibrate" for one second. The current reading becomes the new zero and is saved for next time.
Surface for 2D bubble (hanging frames, tables), Inclinometer for a single angle with protractor, Plumb for vertical walls, Camera for AR overlay on photos.
Tap "Hold" to freeze the reading for note-taking. In Camera mode tap "Save photo" to export a PNG with the angle burned into the image.
Check surfaces, slopes and plumb lines using your phone's accelerometer
Sensor Access Required
This level uses your phone's motion sensors. Tap below to enable them — on iOS, a permission dialog will appear once.
Open on Your Phone
A bubble level needs an accelerometer. Scan this QR code with your phone camera to open the page on a mobile device.
Or type the URL into your phone browser.
Hold the phone vertically against a wall to check for true vertical.
Recent measurements
Features
FAQ
Why does iOS ask for permission?
Since iOS 13, Safari requires explicit permission to read motion sensors. The dialog appears once per device. If you missed it, reload the page and tap "Enable Sensors" again.
Does it work on a desktop computer?
No. A bubble level needs an accelerometer, which desktop computers don't have. Open the page on your phone instead — the desktop view shows a QR code for quick access.
How accurate is a phone-based level?
Modern phones report orientation with about 0.1–0.3° precision after our EMA smoothing. That's enough for picture frames, shelves and DIY carpentry. For professional calibration work, a hardware digital level is still the right tool.
How do I calibrate it correctly?
Place your phone on a surface you know is flat (a kitchen counter, a spirit-level-checked shelf). Long-press "Calibrate" for one second — the tool averages 30 readings over 500ms and saves the offset in your browser.
What's the difference between Surface, Inclinometer and Plumb?
Surface shows a 2D bubble for horizontal alignment in both axes at once — best for tabletops. Inclinometer shows a single big angle for measuring slopes. Plumb shows vertical deviation when the phone is held upright against a wall.
Can I save a measurement?
Yes. The History panel records snapshots you can replay. In Camera AR mode the "Save photo" button exports a PNG with the angle overlaid — handy for sending measurements via messenger.
We can — and it's free! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.
