The mayan calendar contains several units, like longcount, haab and tzolkin. The longcount counts the days since a
mystical zero-date, the 11th August 3114 B.C.. The smallest unit is the Kin = 1 day. The "month" of the longcount is the
Uinal, a period of 20 Kin. 18 of these Uinals are a Tun, this is a period of 360 days. A period of twenty Tun is a Katun
and 20 of such Katun are one Baktun.
Sometimes the mayans used larger values, 20 Baktun are one Pictun, 20 Pictun are one Calabtun, 20 Calabtun are one Kinchiltun,
20 Kinchiltun one Alautun, and 20 Alautun are one Hablatun. This were a period of 1'261'627'548.82 years!
The Tzolkin is a ceremonial calendar of 260 days. More Information about it's function and a theory about it's sense you'll find on my Tzolkin-Page
The Tzolkin works like two toothed wheels. The numeric counting begins at 1 and ends at 13. Each day the name of month will changed. In this manner the fourth Ahau will followed by the fifth Imix.
The Haab is the calendar for the common life and agricultural applications. This calendar contains 18 "months" of 20 days,
and five additional days, to obtain a year of 365 days. The five Uayeb was unfortune-days, the system is equal to the ancient Egyptian.
The counting begins at 0 (!) and ends at 19 of the month, then the next month begins. After the date 0 Cumku follows the 1 Cumku. The last
days of the haab are the Uayeb.
The combination of Tzolkin and haab results in the calendar round (it's working like toothed wheels again). After a period of 52 Haab (or 73 Tzolkin) the day first time has the same name. There existed several system of combination between Tzolkin and Haab, mostly used is the classic system, but in the toltecian period also other systems was used. The same haab-date 0 Pop can only be combined with four of the twenty Tzolkin-Months, but in other systems the 0 Pop was correlated with another Tzolkin-day! The scientist know 3 different systems of such year-bearer. Not enough, in the Mayapan-system the year-bearers was correlated with 1 Pop (in this system the month ended with 0 Pop)!
The using of the year-bearer-systems
The function of the Calendar-Round
The postclassic Mayans didn't keep the using of the longcount. The calendar-round was completed after a cycle of
52 Haab. Most mesoamerican cultures used only this system, but the mayan had additionally the short-count to set the calendar round into a bigger context. This short-count
was used in the classic period too, but continued till the conquest of Yucatan. How did this system work? A katun ends
with a Ahau-Tzolkin-Date, the explanation is easy, both periods are dividible by 20. After each Katun the Ahau-Value
was decreased by 2, so 13 Ahau was followed after a Katun by 11 Ahau (then 9,7,5,3,1,12,10,8,6,4,2 Ahau). In such way
after a cycle of 13 Katun (260 Tun, about 256 Haab) the Tzolkin-Value of the completed Katun was equal.
When Merida was founded, a Katun 13 Ahau finished, this was 1542. Using this knowledge the americanists tried to find a correlation between the longcount and our calendar. Thompson correlated this date with 188.8.131.52.0. of the longcount, Spinden with the 184.108.40.206.0.. The difference between these two dates is 260 Tun, or about 256 years. So the zero-date of Thompson is the 11th August 3114 B.C., the zero-date of Spinden the 14th October 3373 B.C.. Most americanists prefer the use of the Thompson-date, and some C-14-Analysis confirm the 11.16.-Correlation.
The Mayans also used the value of the synodic venus-period, a cycle of 584 days. Five Venus-Cycles are equal to eight haab. The Tzolkin, the Haab and the Venus-Calendar have the same date-value after 104 Haab (or two calendar-rounds).
The big Cycle
The big cylce is a period of 13 Baktun, 260 Katun, 5'200 Tun, 93'600 Uinal or 1'872'000 Kin. It's a value of 7200 Tzolkin, or 8 900-Tzolkin-Cycles of the Time-Gate. And naturally it's the same Tzolkin-date like 0 Baktun.
The Mayan Calendar
Der Kalender der Maya (german)
The Maya Calendar
Maya Calendar by John Major Jenkins
The Classic Maya Calendar and Day Numbering System
Kalenderdaten der Mayas (german)
The Mayan Calendar Date Calculator
Lessons In Maya Calendrics and Writing
Numerical Factors and Periods Important in Maya Calendrics
Mayan Calendrical Mathematics with Python
Mayan Calendar Tools
Robert Bast - The Mayan Calendar
Esoteric aspects of the mayan calendar
December 18, 1999 (Galactic Federation)
All about 2012
Research on the Mayan Calendar
The Sphinx-Group Calendar Convergence
Calendars of various cultures