Caliper

Caliper is an Air-based software application whose purpose is to help you place a virtual ruler on your desktop in order to count pixels. The ruler is placed above all running programs and can be used for measuring anything that appears on your screen.
It proves to be particularly useful especially when you work with CAD programs and need to measure the distances between objects, or simply want to find out the size and position of photos, documents, icons, or other objects.

Simplistic looks and basic features

Pixel Ruler gives you the possibility to move the virtual ruler to any area of the desktop using the drag-and-drop support. On the downside, you cannot run multiple instances of the program, so you are allowed to use a single ruler.
What’s more, you can make use of the built-in slider for expanding the ruler according to your mouse movements. Pixel Ruler automatically displays the value whenever you expand the ruler to the desired screen area. By default, the utility remains on top of other applications. You may also rotate the ruler to different angles but the feature is not implemented well.

Performance

Since it doesn’t comprise any configuration settings, even rookies can master the process with just a few clicks. As it would be expected from such a small utility, it remains light on the system resources, so it doesn’t burden the overall performance of the computer, nor interfere with other programs’ functionality.

Bottom line

All in all, Pixel Ruler comes bundled with limited features for helping you count pixels with the use of a ruler. However, it cannot compete with other powerful tools from the same category, as it doesn’t allow you to customize the ruler, copy data to the clipboard, and adjust the transparency and luminosity, just to name a few suggestions.