The candela per square metre (symbol: cd/m<sup>2</sup>; alternatively titled candela per square meter) is the unit of luminance in the International System of Units (SI). The unit is based on the candela, the SI unit of luminous intensity, and the square metre, the SI unit of area.

The nit (symbol: nt) is a deprecated non-SI name also used for this unit (1 nt = 1&nbsp;cd/m<sup>2</sup>). The term nit is believed to come from the Latin word , "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 . Typically, monitors calibrated for SDR broadcast or studio color grading should have a brightness of . Most consumer desktop liquid crystal displays have luminances of 200 to 300&nbsp;cd/m<sup>2</sup>. HDR displays range from around 400 to 2500&nbsp;cd/m<sup>2</sup>.

Comparison with other units of luminance

One candela per square metre is equal to:

  • 10<sup>−4</sup> stilbs (the CGS unit of luminance)
  • × 10<sup>−4</sup> lamberts
  • apostilbs
  • 0.292 foot-lamberts
  • × 10<sup>3</sup> skots
  • × 10<sup>7</sup> brils
  • 1 nit

See also

  • Orders of magnitude (luminance)
  • Photometry (optics)

References

  • IEC 61966-2-1:1999 Multimedia systems and equipment – Colour measurement and management – Part 2-1: Colour management – Default RGB colour space – sRGB
  • IEC International System of Units zone