What is a Candela per square meter (CD/M2)? The Candela per Square Meter (also known as a Nit) is the base unit used to measure the luminance of a display. The luminance of a display indicates how of how bright the display’s surface will appear to an eye looking at the surface from a particular angle of view. Computer displays used in typical room environments typically exhibit luminances ranging from 50 to 300 cd/m2. For a screen to be viewable under direct sunlight, a luminance of at least 800 cd/m2 is generally required.