Pixel Ace is a powerful pixel ruler utility. Use it to measure the size of objects (in pixels) on your computer, including items behind the ruler. Completely resizable, adjustable transparency, the best pixel ruler out there. Measure items (in pixels) on your computer screen. Use scroll wheel to adjust the transparency of the ruler. Completely resizable. Adjust the size of the ruler to fit your needs. Can drag the bottom right corner of the ruler to make the ruler a box view. This allows you to measure height and width at the same time.