Long Count

The Long Count was the primary method that the Classic Period Maya used to mark time. In essence, the Long Count totals the number of days since a date in the distant past (a similar idea to the Julian Day Number). In most dates carved by the Maya, dates are expressed with five values, called k'in, winal, tun, k'atun, and bak'tun. The Maya also had other terms to denote larger units of time, but these were very rarely used (shown in the table below) of which the pik'tun and k'alabtun are accessible from this program. The complete Long Count includes a Calendar Round date for the given day.

The Maya use a vigisimal (base 20) number system, which works like our decimal (base 10) system. When expressed in writing, each digit was expressed by a glyph. Within the glyph, the digit is indicated by one to four dots with a value of one, and one to three bars with a value of five. By combining the dots and bars, values from one to nineteen could be represented. The value zero was indicated by a shell symbol.

A k'in (the Mayan word for sun) is equivalent to one day. A winal is equal to 20 k'ins. A tun, however, breaks the vigisimal pattern. A tun is equal to 18 winals. This was apparently to make a tun (360 days) roughly equal to a calendar year. A k'atun is equal to 20 tuns, and a bak'tun is equal to 20 k'atuns. Thus each of the figures in the same row in this table are equivalent:

The Maya successfully performed calculations to find the correct Calendar Round on Long Count dates almost half a billion years into the past.

The modern convention for specifying a Long Count is to start with bak'tuns, the largest unit, and end with k'ins, the smallest, separating the units with periods. Thus 9.13.10.5.3 is 9 bak'tuns, 13 k'atuns, 10 tuns, 5 winals, and 3 k'ins. This is followed by the Calendar Round date. The complete Long Count date is 9.13.10.5.3 6 Ak'bal 1 Tzek. The Calendar Round date can be used to check that the numeric portions have been read correctly. This is important when determining dates on stela that have been badly weathered.

The Maya recorded the end of the previous creation as having ended on 13.0.0.0.0 4 Ahaw 8 Kumk'u (August 13, 3114 BC, using the Astronomical correlation constant). In this program, this date is denoted as 0.0.0.0.0 4 Ahaw 8 Kumk'u. In the Maya cosmology, there have been three creations before the current one. We are approaching 13.0.0.0.0 again, and it has been suggested that the current creation will end on that date. That date translates to December 23, 2012 AD. Some argue otherwise, saying that the Maya abbreviated the ending date to 13.0.0.0.0 but the larger units, such as the pik'tun, also need to cycle before the end of creation. A date on a monument in Cobá indicates that at least 19 larger units need to cycle back to 13 before the end of creation, requiring at least 41 x 10²⁷ years. This is a much larger amount of time than since the Big Bang of modern cosmology, which is only 15 x 10⁹ years.