${\displaystyle \frac{{\Phi }_{\max }-{\Phi }_{\min }}{{\Phi }_{\max }+{\Phi }_{\min }}}$

Note 1 to entry: The amplitude of fluctuation can be applied also for "luminance" and "illuminance". Additional photometric quantities can be used.

Note 2 to entry: The amplitude of fluctuation of the luminous flux has unit one and is usually expressed in per cent (%).

Note 3 to entry: This entry was numbered 845-07-66 in IEC 60050-845:1987.