The Long Count (LC) is a count of days extending infinitely into the past and future. It is usually said to be exclusively Maya, but the earliest known LC dates, falling in the 1st century BC, were recorded by the Zoque, who may have invented the system. By the Classic period, at least in terms of surviving monuments with dates, the LC was essentially a lowland Maya calendar.

LC reckonings are tabulated in terms of these basic units or periods:

1 day

20 days

360 days

7200 days

144,000 days

k'in

winal

tun

k'atun

b'aktun

The “b'aktun” label was invented by early epigraphers. The other labels are terms used for time periods by the Yucatec in the 16th century, by which time the LC was used only in a simplified form. Except for “k’in,” the original names of these periods are uncertain. A few inscriptions record larger periods.

With a handful of possible exceptions, LC reckonings are made in terms of very long cycles of 13 bak’tun (about 5100 years). The current cycle began on 21 December 2012, when the world failed to end in a spectacular cataclysm. The previous one, which embraces the period when the ancient Maya were recording dates, began (at 0.0.0.0.0) on 11 August 3114 BC and ended on 20 December 2012. The day before the beginning of that cycle, 10 August 3114 BC, was the final day, 12.19.19.17.19, of an earlier cycle of 13 bak’tun. The LC was not in use in the 32nd century BC; the beginning point of the cycle was a backward projection by calendar specialists who developed the LC some 3000 years later.

Specifying the Gregorian equivalents of LC dates presupposes a particular correlation of the two calendars. The correlation is a complex issue in which colonial period texts, recordings of astronomical observations, and archaeological evidence all come into play. No correlation is entirely consistent with all the available evidence, but it is clear that one or another variant of the Goodman-Martínez-Thompson (GMT) correlation is correct. Correlations are expressed in terms of the Julian Day Number (JDN) of 0.0.0.0.0 of the last 13-bak’tun cycle. (JDNs are a day count invented by astronomers to refer to past time without using particular local calendars). The GMT variants place 0.0.0.0.0 of that cycle on days 584,283 (11 August 3114 BC), 584,285 (13 August 3114 BC), or 584,286 (14 August 3114 BC). The 584,283 (11 August) equation is most widely favored.

LC dates are normally recorded in descending order, beginning with bak’tun. The LC on Tikal Stela 29 – conventionally transcribed 8.12.14.8.15 – records a day 1,243,615 days after 0.0.0.0.0. It corresponds to 6 July AD 292 in the Gregorian calendar. LCs in the codices are even simpler, consisting of columns of numbers representing the number of elapsed periods, without the period signs and without the introductory sign.

8 x 144,000 = 1,152,000 days

12 x 7,200 = 86,400

14 x 360 = 5,040

8 x 20 = 160

15 x 1 = 15

____________

1,243,615 days