Google has released its Measure app for all devices supporting the ARCore technology. The app is now available for download for free on the Google Play Store but you should first install the ARCore app to make it work.
The Measure app is pretty simple and uses the camera on your ARCore compatible smartphone to measure the length or height of objects. It needs a textured surface and good amount of light to work but once it detects a plane you can drag the measuring bar on the screen and place it along the edges of the object you want to measure. After that you can choose to save an image for sharing.
In my usage, the app worked perfectly fine on a OnePlus 6. The measurements it generated were also reasonably close to what a measuring tape indicated. For serious stuff, it's best to use a tape but if you just need a rough estimate then this can be quite useful.
The app was previously only available to Google Tango devices. However, it seems Apple's decision to include its own AR measuring app in iOS 12 seems to have changed Google's mind, and so the app is now available to every ARCore compatible device. Or maybe it's just a coincidence.