If you are looking for an easy-to-use and reliable tool to measure the diameter of any objects, whether it is a round or a square shape, then the ON Diameter app is the best choice. This is an Android tool that is designed to measure the diameter of any objects. It will help you to measure the area of any circles. 

How to use it?

The first thing you have to do is to open the application and click on the menu option "Settings". In the next page, you will be asked to do the calibration. The calibration will be needed for the first time you launch the application. 

After the calibration, you will be ready to use it. The first thing you have to do is to select the measured object. Then, you will be asked to place it anywhere on the screen. You will be given a preview of the result.