How to Use the Hidden Built-In Spirit Level on an iPhone

If you are hanging a picture frame, installing a new shelf, or trying to determine if your desk is perfectly flat, you do not need to rummage through your garage for a physical bubble level. Your iPhone contains highly sensitive, internal gyroscopes and accelerometers that are perfectly capable of measuring physical slopes with pinpoint accuracy.

Apple used to hide this digital spirit level inside the standard Compass app. However, in recent versions of iOS, they moved the feature into a dedicated, highly versatile utility app.

How to Access the Spirit Level

1. Unlock your iPhone and swipe down on the middle of the home screen to open the Spotlight Search bar.
2. Type Measure into the search box.
3. Tap the official Apple Measure app (the icon features a yellow ruler on a black background).
4. Look at the very bottom of the screen. You will see two tabs: “Measure” (which uses augmented reality to estimate distances) and “Level”.
5. Tap on the Level tab.

How to Use the Level (Flat Surfaces)

If you want to check if a table or floor is perfectly flat (horizontal):

1. Place your iPhone flat on its back directly on the surface you are testing.
2. Look at the screen. You will see two white circles and a degree readout (e.g., 2°).
3. The goal is to align the two circles perfectly. If the table is tilted, the inner circle will drift away from the center.
4. When the surface is perfectly flat (0°), the entire screen will flash a bright, highly visible Green.

How to Use the Level (Vertical Edges)

If you are hanging a picture frame and need to check if the side edge is perfectly straight (vertical):

1. Hold your iPhone upright (in portrait orientation).
2. Press the side edge of the iPhone flush against the side of the picture frame or wall.
3. The screen will display a horizontal line dividing a black and white background.
4. Tilt the phone left or right until the degree readout hits 0° and the lower half of the screen turns solid Green.

Pro Tip: If you are working on a custom project (like building a ramp) and need to match a specific, non-zero angle, you can tap the screen once to “lock” the current angle. The screen will turn red if you deviate from that specific custom angle, allowing you to perfectly replicate complex slopes.