Perpetual calendar - Definition and Overview

A perpetual calendar is a calendar which is good for a span of many years, such as the Runic calendar.

For the Gregorian calendar, a perpetual calendar often consists of 14 one-year calendars, plus a table to show which one-year calendar is to be used for any given year. Note that such a perpetual calendar fails to indicate the dates of moveable feasts such as Easter.

The Perpetual Calendar has 14 one-year calendars, one for each common year (year that does not have a February 29) that starts on each day of the week, and one for each leap year that starts on each day of the week.

Common year starting on Sun - Mon - Tue - Wed - Thu - Fri - Sat
Leap year starting on   Sun - Mon - Tue - Wed - Thu - Fri - Sat

Also certain calendar reforms may be considered to be perpetual calendars, such as the World calendar and International Fixed Calendar.