Kelvin Color Temperature Scale

The Kelvin Scale is used to measure CCT. While it may be counterintuitive, the lower the color temperature, the “warmer” the light appears (ex. reddish is in the 1,000 range).

The correlated color temperature (CCT) of a light source is a numerical measurement of its color appearance. This is based on the principle that any object will emit light if it is heated to a high enough temperature, and the color of that light will shift in a predictable manner as the temperature is increased.

The system is based on the color changes of a theoretical “blackbody radiator” as it is heated from a cold black to a white hot state. With increased temperature, the blackbody would shift gradually from red to orange to yellow to white and, finally, to a blue white. A light source’s CCT, then, is the temperature, measured and expressed in degrees Kelvin (K), at which the color of the blackbody would exactly match the color of the light source.