Under continued use, a monitor’s white color temperature and brightness change gradually over time.

Assume a monitor’s color temperature was set to 5,000 K and its brightness to 100 cd/m² when purchased. Since these values will change with time under continued use, a few months later the white will have become warmer and the brightness will have dimmed, to 4,500 K and 90 cd/m² , respectively.

For this reason, calibration is important to return the monitor to its original state—i.e., to a color temperature of 5,000 K and a brightness of 100 cd/m² .

When using a monitor for graphics, stable color can be maintained at all times by conducting calibration at a frequency of once every 200–300 hours.

An LCD monitor used for graphics should be calibrated at least once every 200–300 hours (in ordinary use, once per month)