Bubble Level

Turn your phone into a level

Bubble Level by Gamma Play uses your Android phone to check whether a surface is level or tilted. It suits straightforward household and workshop jobs such as aligning a picture or checking a shelf, and can also help when positioning a camera tripod. The app is in the Tools category and has 10,000,000+ installs.

What it measures

The app imitates a traditional spirit level, where a bubble shows when a surface is tilted. It also includes a circular, bull’s-eye style level for checking a surface across a plane, rather than along a single direction. That makes the two displays useful for different kinds of alignment checks. The result depends on the phone’s sensors and how it is placed, so this is a phone-based substitute for a physical level, not a separate measuring instrument.

Calibration and practical limits

The supplied description says the phone should be calibrated by its manufacturer and provides an option to set a calibration on a surface believed to be level, or reset it to the device’s factory calibration. If readings seem wrong, calibration is relevant before relying on them. For work where a small error matters, check the result with a physical level rather than assuming the phone is accurate.

What the listing tells you

Bubble Level has a 4.69-star rating from 335,046 ratings, alongside its 10,000,000+ installs. Those figures indicate broad use and many user ratings, but do not show whether the app contains advertising, offers paid items, or requests particular phone permissions. The available details also do not establish what, if anything, you would need to pay for. Check the Google Play listing for those terms before deciding whether to use it.