jRuler

In order to determine the size of objects on your desktop a dedicated tool is required. This is where jRuler comes in, ready to give you a helping hand in measuring the scane of any small window, image or any other item.
Built using the Java programming language, this lightweight utility does not require installation and it can be launched with just a double click. It displays a square-shaped measuring tool with graduation on each side, measuring dimensions in inches only.
On the downside, you cannot adjust the position of the squared ruler. This means that you have to bring the object to the ruler, instead of putting the ruler on top of the target, which is a bit incomfortable. However, pressing the 'window' symbol in the main interface automatically transforms the ruler into a movable, standard window that can be moved around the desktop and placed wherever you want.
The application allows you to run it in multiple instances and launching a new ruler is as easy as pressing a button. To be more precise, the colored button within the GUI that is split into four sections. Pressing the left part opens the new instance to the left and the same goes with the right, up and down areas. Therefore, you can run a maximum of five rulers simultaneously.
jRuler could use some improvements to make it more accessible, but it can be of use in graphic painting, for measuring tiny objects. While there are various online virtual rulers that can help you in this matter, not to mention the dedicated tools integrated in graphic design applications, this small utility can do just as much.