A comparison of various formulae used for determining the degree of whiteness has led to a new, simple and universally applicable formula, the Ciba-Geigy formula, which has been successfully used in routine tests and which for the first time gives different weight to whiteness values corresponding to all shade preferences existing in theory (shade preference for fluorescent white without changes in the values for neutral shades of white). Each user of the formula is in a position to determine for himself his own parameters by means of a simple calcu-lation and to give quantitative data on his own shade preferences. It was also found that with another formula the shades of fluorescent whitening effects (green to red tints) may be defined in a simple way. Parameters for the two formulae have been determined and checked by means of an automatic color filter photometer equipped with an easily programmable minicomputer. -- AATA