Mesoamerican Long Count calendar

The Mesoamerican Long Count calendar is a non-repeating, vigesimal (base-20) and base-18 calendar used by several Pre-Columbian Mesoamerican cultures, most notably the Maya. For this reason, it is sometimes known as the Maya (or Mayan) Long Count calendar. Using a modified vigesimal tally, the Long Count calendar identifies a day by counting the number of days passed since a mythical creation date that corresponds to August 11, 3114 BCE in the Gregorian calendar. The Long Count calendar was widely used on monuments.

Representation	Long Count subdivisions	Days	~ solar years
0.0.0.0.1	1 k'in	1	1/365
0.0.0.1.0	1 winal = 20 k'in	20	0.055
0.0.1.0.0	1 tun = 18 winal	360	0.986
0.1.0.0.0	1 k'atun = 20 tun	7,200	19.71
1.0.0.0.0	1 b'ak'tun = 20 k'atun	144,000	394.3

Long Count	Gregorian dateGMT (584283) correlation
13.0.0.0.0	August 11, 3114 BCE
1.0.0.0.0	November 13, 2720 BCE
2.0.0.0.0	February 16, 2325 BCE
3.0.0.0.0	May 21, 1931 BCE
4.0.0.0.0	August 23, 1537 BCE
5.0.0.0.0	November 26, 1143 BCE
6.0.0.0.0	February 28, 748 BCE
7.0.0.0.0	June 3, 354 BCE
8.0.0.0.0	September 5, 41 CE
9.0.0.0.0	December 9, 435
10.0.0.0.0	March 13, 830
11.0.0.0.0	June 15, 1224
12.0.0.0.0	September 18, 1618
13.0.0.0.0	December 21, 2012
14.0.0.0.0	March 26, 2407
15.0.0.0.0	June 28, 2801
16.0.0.0.0	October 1, 3195
17.0.0.0.0	January 3, 3590
18.0.0.0.0	April 7, 3984
19.0.0.0.0	July 11, 4378
1.0.0.0.0.0	October 13, 4772

The previous creation ended on a long count of 12.19.19.17.19. Another 12.19.19.17.19 will occur on December 20, 2012, followed by the start of the fourteenth b'ak'tun, 13.0.0.0.0, on December 21, 2012.