- Types of Calendar
Lunar, solar, lunisolar, rule-based, etc.
- The Julian and the Gregorian Calendars
The Julian Calendar, the Gregorian reform and its adoption, astronomical year numbering,
the Julian and the Gregorian Proleptic Calendars, and the accuracy of calendars.
- The ISO 8601 Date Format
A note concerning date formats, especially the ISO 8601 date format.
- Julian Day Numbers
The nature and origin of the Julian day number system.
- Chronological Julian Date
An explanation of the concept with examples of use.
- The Hermetic Leap Week Calendar
A calendar with an integral number of 7-day weeks in each year, and which stays in sync with the seasonal year.
- The Hermetic Lunar Week Calendar
A solilunar calendar which avoids the problem of rescheduling with each new year.
- The Archetypes Calendar
An accurate lunar calendar with (mostly) weeks of 10 days.
- Why Seven Days in a Week?
Why not six or eight?
- The Structure of the Chinese Calendar
How the Chinese Calendar depends on the times of astronomical events.
- The Maya Calendar
Links to an explanation of Maya and European Dates, the correlation problem, and the yearbearer systems.
- The Liberalia Triday Calendar
- The Meyer-Palmen Solilunar Calendar
- Writings by Others
Articles by renowned calendrical scientists Karl Palmen, Simon Cassidy, Duncan Steel, Lance Latham, the Böhm brothers and others.
- Easy Date Converter
A conversion program which gives you the day of the week for a date, the Julian day number and more, and allows date arithmetic: adding a number of days to a date, etc., with or without inclusion of weekend days. In English and German.
- Equinoxes, Solstices and Cross-Quarter Days
For calculating accurate dates and times of equinoxes, solstices and the Celtic cross-quarter days for any year in the range 1 CE through 3000 CE (for both hemispheres).
- Lunar Calendars and Eclipse Finder
Software for conversion among dates in the Common Era and Julian Calendars and dates in several lunar calendars. The program also finds the dates, times and durations of solar and lunar eclipses.
- Chinese Calendrics
Software for converting between Chinese and Western dates and for obtaining other information such as the dates of Chinese New Year's Day for any year.
- Julian-Gregorian-Dee Date Calculator
Converts between Julian, Gregorian, Dee and Dee-Cecil calendar dates in various formats, and adds and subtracts a number of days, weeks, months and years to or from a given date.
- Mayan Calendrics
Converts among Maya and European dates in various calendar systems. In English and German.
- Printable Calendar
A modest utility to help you keep track of things to do.
- Printable Hermetic Lunar Week Calendar
Same but different.
- Identical Calendar Years
How long do you have to wait before you can re-use that old wall calendar that you like so much?