You may want to use the Mayan calendar tools here to calculate and covert Mayan dates to and from Gregorian calendar dates. and understand the infinite play schedule and events. Another good one is here

The amazing things about the Mayan Calendar are:

The periods / cycle that it tracked, far beyond the lifespan of the human body today the longest being 63 million years.
The accuracy and understanding they needed pin point an astronomical event 2300 in the future.
That the calendar counts down to a very specific date and time coinciding with a specific event.
There were three calendars only one served as a standard agricultural calendar

What did they know that we do not or perhaps forgot?

What was the event or events that would occur at this endpoint and new beginning?

This means that the end date of 13.0.0.0.0, some 5125 years later, is December 21st, 2012 A.D.1

The Mayan Calendar

Number of Days / Term 1 / Kin (day) 20 / Uinal 360 / Tun 7200 / Katun 144000 / Baktun

1 pictun = 20 baktun = 2,880,000 days = approx. 7885 years
1 calabtun = 20 pictun = 57,600,000 days = approx. 158,000 years
1 kinchiltun = 20 calabtun = 1,152,000,000 days = approx. 3 million years
1 alautun = 20 kinchiltun = 23,040,000,000 days = approx. 63 million years

Among their other accomplishments, the ancient Mayas invented a calendar of remarkable accuracy and complexity. At right is the ancient Mayan Pyramid Chichen Itza, Yucatan, Mexico. The Pyramid of Kukulkan at Chichén Itzá, constructed circa 1050 was built during the late Mayan period, when Toltecs from Tula became politically powerful. The pyramid was used as a calendar: four stairways, each with 91 steps and a platform at the top, making a total of 365, equivalent to the number of days in a calendar year.

The Maya calendar was adopted by the other Mesoamerican nations, such as the Aztecs and the Toltec, which adopted the mechanics of the calendar unaltered but changed the names of the days of the week and the months.

The Maya calendar uses three different dating systems in parallel, the Long Count, the Tzolkin (divine calendar), and the Haab (civil calendar). Of these, only the Haab has a direct relationship to the length of the year.

A typical Mayan date looks like this: 12.18.16.2.6, 3 Cimi 4 Zotz.

12.18.16.2.6 is the Long Count date.
3 Cimi is the Tzolkin date.
4 Zotz is the Haab date.

What is the Long Count?

The Long Count is really a mixed base-20/base-18 representation of a number, representing the number of days since the start of the Mayan era. It is thus akin to the Julian Day Number.

The basic unit is the kin (day), which is the last component of the Long Count. Going from right to left the remaining components are:


uinal	(1 uinal = 20 kin = 20 days)
tun	(1 tun = 18 uinal = 360 days = approx. 1 year)
katun	(1 katun = 20 tun = 7,200 days = approx. 20 years)
baktun	(1 baktun = 20 katun = 144,000 days = approx. 394 years)

The kin, tun, and katun are numbered from 0 to 19.
The uinal are numbered from 0 to 17.
The baktun are numbered from 1 to 13.

Although they are not part of the Long Count, the Mayas had names for larger time spans. The following names are sometimes quoted, although they are not ancient Maya terms:

The alautun is probably the longest named period in any calendar.

What is the Tzolkin?

The Tzolkin date is a combination of two "week" lengths.

While our calendar uses a single week of seven days, the Mayan calendar used two different lengths of week:

a numbered week of 13 days, in which the days were numbered from 1 to 13
a named week of 20 days, in which the names of the days were:

What is the Haab?

The Haab was the civil calendar of the Mayas. It consisted of 18 "months" of 20 days each, followed by 5 extra days, known as Uayeb. This gives a year length of 365 days.