Ultraviolet B (UVB) treatment is most often performed according to a fixed schedule, not necessarily considering important variables such as UV intensity, type of UVB source and skin pigmentation. These variables can rather easily be taken into consideration by the right choice of dosing unit. The advantage of going from dosing in time to Joule to standard erythema dose or to minimal erythema dose is considered. The size of most variables may be diminished considerably. Following these guidelines, it is possible to increase the efficacy of UVB phototherapy without increasing the risk of unintentional burning.