The most unexpected everyday tool can be found on your phone

Apple

The best way to measure something is still a tried-and-true tape measure. But if you don't have one on hand, your iPhone has a built-in tool that uses the camera (and, on Pro models, LiDAR) to get the job done.

If you didn't know that, well, you aren't alone. After releasing the tool in 2018, Apple hasn't exactly promoted the app. It merely sits in the Utilities folder, waiting (perhaps in vain) to be discovered.

Filipe Espósito for Engadget

Unless your iPhone is truly ancient, you should have the Measure app. It came preinstalled on every model from the iPhone 6s and first-gen iPhone SE onward. If you deleted it at some point, you can redownload it from the App Store.

But Pro models get a better version. Apple added a LiDAR scanner starting with 2020's iPhone 12 Pro, and it's remained in all subsequent Pro-series iPhones. LiDAR fires invisible lasers to judge depth, making Measure more useful. It includes instant height measurements of people, guide lines that snap to edges, a ruler view with tick marks when you get close and a list of measurements from the current session.

Apple

Each time you open the app, you'll need to slowly move your phone around. This lets it map your surroundings so it can accurately measure things.

Once it finishes that initial scan, you can start measuring. Aim the dot at one end of the object you want to measure and tap the + button. Then, move the camera view to the other end and tap + again. Presto: The length appears on the screen.

You can tap the shutter button to save a screenshot to Photos. If you need to go back, there's an undo button; if you want to start over, tap the clear (trash can) icon. Pro models keep a list of your measurements, but only until you close the app. So if you need to revisit them later, copy them into another app or save a snapshot to Photos.

The app can also automatically measure rectangles. If it detects the edges of a rectangular object, a white box will appear around it. Tap the white box or the + button to see the dimensions.

There's a Level tab at the bottom of the screen too. Tap that, lay your phone flat on something like a shelf or a hanging picture frame and it will show you how many degrees you're off by. You can also compare the slopes of two surfaces: tap the screen to capture the first angle, then place the iPhone on another surface and rotate it until the screen turns green.

There are times when it's nice to have a digital tape measure in your pocket. Heading to the airport? Whip out your phone to check if your carry-on bag is within the airline's limits. It could come in useful while out shopping, too, when you're less likely to have a tape measure on hand. If you see a piece of furniture you like, point your phone at it and compare it to your home measurements to see if it fits.

For anything high-stakes, like a project that's expensive or potentially dangerous, use a real tape measure. Apple says its app works best for objects with clear edges about 2 to 10 feet away. Even then, it's best treated as a quick, on-the-fly check, not something definitive.

Android will soon no longer have a direct, first-party equivalent to Apple's Measure app. Google once did, but it was never quite as stable as Apple's, and the company quietly abandoned it in 2021. Meanwhile, Samsung's Quick Measure app, which came preinstalled on some Galaxy phones, is shutting down at the end of 2026. Until then, you can still download it, and Samsung says it should keep working after the cut-off date. The company claims the app will return at an unspecified future date, "with improved services."

Otherwise, third-party apps are the main option for Android users. No mainstream Android phone has a built-in LiDAR scanner like the Pro-series iPhones, so these apps are working with a more limited toolset. And reviews suggest that those in the Play Store are often plagued with ads and aggressive in-app subscription prompts. So, if you have an Android phone, your best bet may be to go analog and invest in one of those tiny keychain tape measures.