The candela per square metre (cd/m2) is the derived SI unit of luminance. The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area.
Nit (nt) is a non-SI name also used for this unit (1 nt = 1 cd/m2). The term nit is believed to come from the Latin word nitere, to shine.
As a measure of light emitted per unit area, this unit is frequently used to specify the brightness of a display device. The sRGB spec for monitors targets 80 cd/m2. Typically, calibrated monitors should have a brightness of 120 cd/m2. Most consumer desktop liquid crystal displays have luminances of 200 to 300 cd/m2. High-definition televisions range from 450 to about 1500 cd/m2.
Comparison to other units of luminance
One candela per square metre is equal to:
References
Candela per square metre Wikipedia(Text) CC BY-SA