Mesoamerican Calendars

``The Mesoamerican calendar, one of the most
  sophisticated timekeeping systems ever
  conceived by ancient people.''
  -- Anthony F. Aveni, Skywatchers of Ancient Mexico

Extensive evidence shows that Prehispanic Mexicans had, from immemorial time and obtained as a result of prolonged astronomical and meteorologic observations, calendrical systems to measure the passage of time.

The following table lists the precision of several calendars including the Maya, considered the hallmark of the Mesoamerican calendar.

Year Duration in days
Hebrew Calendar* 365.246827
Julian Calendar365.250000
Gregorian Calendar365.242500
Mayan Calendar365.242129
Astronomical calculation365.242198
*(The Year of Rabbi Adda)

These calendars had enormous importance in daily life, in ceremonies and festivals, in the agriculture, and in the complexity of their religious thought and cosmovision.

Two were basically the calendrical systems from where other chronological calculations were developed in a precise and complex manner. One was the civil or solar calendar, of 365 days, made up of 18 sets of twenty days ("veintenas") plus 5 more days at the end. Throughout those 365 days another calendar system provided names to those days based on an astrological and ritual basis in cycles of 260 days. In this calendar, there were 4 divisions of 65 days, each subdivided in 5 periods of 13 days ("trecenas").

The count of days and destinies were carried out by means of numerals, from 1 to 13, that in combination with 20 day signs formed a unique sequence of 260 days. In order to indicate a date with precision, it was necessary to represent the combination of numeral and day sign, and also the name of the month or veintena.

In addition, as a consequence of the introduction of the extra five days at the end of the solar year, only 4 day signs could be the markers or year bearers, i.e., the day signs of the day that would name the year. Among the Mexica, these 4 day signs were Acatl (Reed), Tecpatl (Flint), Calli (House), Tochtli (Rabbit). Combining again those 4 day signs with the numerals from 1 to 13 results in 52 years, the so called Binding of the Years, whose end was observed in special ceremonies for the kindling of a "New Fire".

Among the Olmec and the Maya another chronological measure was in use, the Long Count represents a count of days from a distant origin.

The following sections presents a more detail discussion of the Maya and Mexica calendars.

Maya Long Count

              12. 18. 17. 16. 6.  6-Cimi  19 Kayab
               /   /   /   /  /   \   \    \   \
 Baktun = 20 K/   /   /   /  /     \   \    \   \__ Month [19]
                 /   /   /  /       \   \    \
 Katun = 20 Tun_/   /   /  /         \   \    \____ Day (0-19)
                   /   /  /           \   \
 Tun = 18 Uinals__/   /  /             \   \_______ Sign [20]
                     /  /               \
 Uinal = 20 kins____/  /                 \__________ Numeral (1-13)
                      /            \--v--/ \---v---/
 kin = 1 day_________/             Tzolkin   Haab
            ^--Baktun Count----^     Calendar Round

Long Count or initial series counts the number of days since creation, Aug 12, 3113 B.C. (according to the GMT or Goodman-Martinez-Thompson correlation.)

       Baktun count (days) = (((B*20 + K)*20 + T)*18 + U)*20 + kins
                          = 144000*B + 7200*K + 360*T + 20*U + kins
The Mayan Calendar Round is composed of the Tzolkin and the Haab. The Tzolkin is the name given to the period of 13x20 = 260 days and includes a numeral (1-13) and one of twenty signs (names).

The Haab is a civil year of 19 months, 18 of them with 20 days numbered from 0 to 19, and the last month with 5 days numbered 0 to 4. The months of the Haab are listed in Table 1.

TABLE 1. Maya and Nahua Months

UoFrogAtlcahualcoDeparture of the waters
ZipStagTlacaxipehualiztliFlaying of men
ZotzBatTozoztontliLittle Vigil
TzecSkullHueytozoztliGrand Vigil
XulEndToxcatlDry Thing
YaxkinTender sun (green)EtzalcualiztliMeal of Corn and Bean
MolReunionTecuilhuitontliLittle Feast of Lords
ChenWellHueytecuilhuitlGrand Feast of Lords
YaxGreenMiccailhuitontliLittle Feast of The Dead
ZacWhiteHueymiccailhuitlGrand Feast of The Dead
MacCoverPachtontliSmall Hay
KankinMature sun (yellow)HueypachtliLarge Hay
PaxMusicPanquetzaliztliRaising of the Banners
KayabTurtleAtemoztliLowering of water
CumhuDark GodTitlShrinking
UayebSpectersNemontemiEmpty Days

The names of the Mexica months and their meanings are also listed in table 1. It is worthy to note that the Maya and Nahuas began their New Year at different times, and hence the months do not correspond as listed.

Month names in Mayan (222 Kb) Month names in Nahuatl (246 Kb).
(Voice of Ricardo Salvador)

Mexica (Aztec)

      Xihuitl: 5-Acatl. Tonal: 6-Miquiztli. Meztli: Tecuilhuitontli 1
        |      |    |     |    |    |          |         |          |
      Year    1-13 Sign  Day   1-13 Sign     Month     Name [19]  Day#

The Aztec (also known as Mexica or Nahua) calendar is derived from the Maya but excludes the long count and adds a year name which is also formed with a numeral (1-13) and 1 of 4 signs in a cycle of 52 years (Xiuhmolpilli). The 260- day period is known as Tonalpohualli and the 365-day year as Xiuhuitl. The correlation with the Gregorian calendar is due to Alfonso Caso. [1]

The signs of the days are in Table 2. The column indicated by the label ``Order'' represents the name of that numeral. For instance, in Nahuatl, Ce is 1, Ome is 2, and so on.

TABLE 2. Sign Meanings

Mi (0)ImixCe (1)CipactliCrocodile
Hun (1)IkOme (2)EhecatlWind
CaAkbalYeiCalliUnderworld, House
OxKanNahuiCuetzpallinRipeness, Lizzard
Ho-LahunCibCaxtolliceCozcacuauhtliOwl, Vulture
Uac-LahunCabanCaxtollomeOllinMovement, Earthquake
Uuc-LahunEznabCaxtollyeiTecpatlKnife, Stone
Bolon-LahunAhauCempohualliXochitlLord, Flower

The glyphs for each day sign can be counted counterclockwise from the top on the third ring of the Aztec sunstone.

Sign names in Mayan (384 Kb) Sign names in Nahuatl (415 Kb).
Finally, many other Mesoamerican cultures, notably the Olmecs who are credited with the invention of the Mesoamerican calendar, had adopted similar calendars as the Mayas and the Aztecs. Such was the case of the Zapotecs, Mixtecs, Otomies, Tarascans, and many others, some of which continued to preserve their calendar. [1,2]

The Tarascans or Purepecha had a similar calendar as the Aztecs, but started the year on different days. The Zapotecs are believed to have invented the Mesoamerican ritual calendar of 260 days. Their calendar then presents 4 subdivisions of that period of 65 days (Cocijo) with smaller subdivisions of 13 days (Cocij) named according to the name of the first day.

As far as correlation to the Western calendar is concerned, the most common ones are mentioned in the references.


  1. Caso, Alfonso, Los Calendarios Prehispánicos, México,UNAM, 1967.
  2. Sharer, Robert, The Ancient Maya, 5th Edition, Stanford University Press, 1995.
    ``And if, on the winter solstice of 2012, human beings witness the beginning of Baktun 13, some of them will be members of the civilization that invented that count.''
    -- Ronald Wright, Time Among the Maya
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