Only perpetual calendars meet the basic condition of allowing the deduction of any of their essential data from the others (the numbers of the year, month, week and day). But almost all known analog perpetual calendars have little of perpetual, their calculations are limited to about 50 years.

This calendar runs from January 1, 1600 to December 31, 2799. It is based on the 400 year repeating cycle and the solar cycle which is 28 years.It works by the "Sunday letter". (H 27).

Measurements:

Diameter: 9cm / Thickness: 0,6cm