Mired

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Derived from the term micro reciprocal degree, the mired (M) is a unit of measurement equal to 1,000,000 (one million) divided by the given color temperature, as per the formula:

where M is the mired value desired, and K is the color temperature expressed in kelvins (former name degrees Kelvin or Kelvin degrees).

Hence, a blue sky, which has a color temperature T of about 25,000 K, has a mired value of M=40 mireds, while a standard electronic photography flash, having a color temperature K of 5000 K, has a mired value of M=200 mireds.

The mired is an especially convenient color temperature scale in photography, where it can be used to indicate color-correcting filter density for a given film and light source. It is sometimes preferred to using simple color temperatures, as it can be considered more intuitive. That is, mired values seem to correspond more appropriately to given colors, and our perception of them, than color temperature values given in kelvins.

For convenience, 'decamireds' (dM) are sometimes used, each decamired containing 10 mireds.

The reverse computation

can be used to extract a color temperature value from a mired value, so that M=80 mireds corresponds to a color temperature of T=12,500 K.