Abstract: A calculator for continuously exhibiting the status of an individual's Bio-Rhythm cycles and, in particular, an individual's physical, emotional and intellectual Bio-Rhythm cycles. The calculator comprises a display panel having three dial faces corresponding to the three Bio-Rhythm cycles and each having indicia thereon defining the critical days within its particular cycle. Indicating elements are provided to sequentially scan each of the dial faces wherein the physical dial face is scanned once in a 23 day period, the emotional dial face once in a 28 day period and the intellectual dial face once in a 33 day period. A high or low critical day in any one of the Bio-Rhythm cycles is defined when the position of an indicating element corresponds to the critical indicia on a dial face. The calculator may be personalized by appropriately presetting the indicating elements relative to their dial faces based on data derivable from an individual's birth date.