How Computer Mice Work

Optical Mouse Accuracy

A number of factors affect the accuracy of an optical mouse. One of the most important aspects is resolution. The resolution is the number of pixels per inch that the optical sensor and focusing lens "see" when you move the mouse. Resolution is expressed as dots per inch (dpi). The higher the resolution, the more sensitive the mouse is and the less you need to move it to obtain a respon­se.

Most mice have a resolution of 400 or 800 dpi. However, mice designed for playing electronic games can offer as much as 1600 dpi resolution. Some gaming mice also allow you to decrease the dpi on the fly to make the mouse less sensitive in situations when you need to make smaller, slower movements.


Historically, corded mice have been more responsive than wireless mice. This fact is changing, however, with the advent of improvements in wireless technologies and optical sensors. Other factors that affect quality include:

  • Size of the optical sensor -- larger is generally better, assuming the other mouse components can handle the larger size. Sizes range from 16 x 16 pixels to 30 x 30 pixels.
  • Refresh rate -- it is how often the sensor samples images as you move the mouse. Faster is generally better, assuming the other mouse components can process them. Rates range from 1500 to 6000 samples per second.
  • Image processing rate -- is a combination of the size of the optical sensor and the refresh rate. Again, faster is better and rates range from 0.486 to 5.8 megapixels per second.
  • Maximum speed -- is the maximum speed that you can move the mouse and obtain accurate tracking. Faster is better and rates range from 16 to 40 inches per second.