GEDCOM Date Calculator
A free utility for converting dates between Gregorian, Julian, Hebrew, and French Republic calendars and for doing calculations on dates such as finding time spans or adding and subtracting time spans to dates. The Date Calculator is available for MacOS or Windows. The Date Calculator can work with fuzzy dates (such as just a year and a month) and still do conversions and calculations. Such fuzzy date calculations are useful for genealogists working with less than complete date information.