When hanging a picture frame or installing a new shelf, ensuring the object is perfectly straight is critical. While a traditional bubble spirit level is the standard tool for the job, you rarely have one readily available when you actually need it. Fortunately, your iPhone contains a highly accurate, built-in digital spirit level that utilizes the device’s internal gyroscope and accelerometer. Oddly, Apple does not advertise this feature prominently; it is hidden entirely within the standard Measure application.
Locating the Level Tool
In older versions of iOS (prior to iOS 12), the spirit level was controversially hidden inside the Compass app. Today, it resides in a more logical, though still obscured, location.
- Unlock your iPhone and swipe down on the home screen to open the Search bar.
- Type Measure into the search field.
- Tap the Measure app icon (a black background with a yellow ruler).
- At the very bottom of the screen, you will see two tabs: “Measure” and “Level”.
- Tap the Level tab on the bottom right.
Measuring Horizontal Surfaces (Flat on a Table)
The application has two distinct operational modes depending on how you hold your iPhone. The first mode is designed for checking flat horizontal surfaces, such as determining if a desk or washing machine is perfectly balanced.
Place your iPhone completely flat on its back (the screen facing the ceiling) on the surface you want to test. The screen will display two overlapping white circles on a black background.
As you tilt the surface (or your phone), the circles will drift apart, and a number will appear indicating the exact degree of incline. Your goal is to align the two circles perfectly. When the surface reaches a 0-degree incline, the screen will flash a bright green colour, confirming the object is perfectly level.
Measuring Vertical Surfaces (Hanging Pictures)
The second mode is designed for vertical alignment, which is essential when hanging picture frames or checking the plumb of a wall.
Hold your iPhone upright in portrait or landscape mode and press the side edge of the phone directly against the object you are measuring. The interface will instantly shift from overlapping circles to a horizontal line dividing the screen.
The lower half of the screen represents the “heavy” side of the incline. As you pivot your phone, the degree measurement in the centre will change. When the edge of the phone is perfectly vertical (or perfectly horizontal in landscape orientation), the degree marker will hit 0, the dividing line will vanish, and the entire screen will turn bright green.
Accounting for Camera Bumps
Modern iPhones feature substantial camera bumps protruding from the rear glass. If you attempt to use the horizontal leveling mode by placing the phone flat on its back, the camera bump will artificially elevate one corner, resulting in a wildly inaccurate reading. For maximum precision on flat surfaces, you should always place the phone face-down so the flat glass screen rests flush against the object. Alternatively, use a thick protective case that perfectly evens out the back panel of the device.