Photo Ruler is designed to accurately determine the size of any object by either taking a picture of it or measuring it on the screen. With its simple user-friendly design. It allows you to measure things just as conveniently and precisely as with a traditional ruler or tape measure. Firstly, ensure that the object you wish to tape measure and the material or object of known length is in the same picture. There is a predefined list of Base Items in the ruler app settings, including Debit/credit card and Quarter. Use the Base Item which is closest in size to the object you wish to tape measure using the Ruler app. Secondly, ensure that the Base Item and the object you wish to tape measure using the Ruler app are in the same plane and the ruler app camera is parallel to them. This is very necessary to avoid image distortions caused by the ruler app camera perspective. Align the Blue arrows against the Base item and Green arrows against the object you want to tape measure. The length of the measured object is shown on the Ruler app screen. Use screen as a traditional mm ruler app. You can easily tape measure the size of a small object by placing it on the device screen. And it adjusting line limiters against the object. If you see that the mm ruler app scale is visually shrunken/stretched. you can easily reset mm ruler app calibration manually. Choose between Imperial and Metric mm ruler Given that you have accurately aligned markers. you will receive a measure that is as precise as when using a traditional mm ruler app or tape measure tool. you can download this app apk file for free. Download now.