The subject invention relates to a method and a device for aiding users in determining the correct correspondence between infant clothing size and meteorological season, based on infant birth date. The method includes using an infant clothing sizing chart with a plurality of rows that correspond to an infant birth date and a plurality of rows that correspond to one of a meteorological season or an infant clothing size. The user cross-references a row and a column of interest to find a point, or cell, or intersection, wherein the point, or cell, of intersection indicates either the appropriate size or season for which infant clothing should be purchased. The subject device, on the other hand, receives user input related to the infant's birth date and one of the meteorological season or the infant clothing size, manipulates the inputted data, and outputs either the appropriate size or season for which infant clothing should be purchased.