Maya Long Count Calendar

About Maya Long Count Calendar

The Maya Long Count is the arithmetical backbone of Classic Maya chronology, a positional day-count calendar that the scribes of Tikal, Palenque, Copan, Yaxchilan, Quirigua, and Coba used to anchor historical and mythological events to a fixed starting point. Unlike the Tzolkin and Haab, which repeat on cycles of 260 and 365 days, the Long Count does not repeat within any human timescale. It counts days linearly from a mythological creation date, written 13.0.0.0.0 4 Ajaw 8 Kumku and corresponding in the standard correlation to 13 August 3114 BCE. Every Maya inscription that bears a Long Count date specifies exactly how many days have elapsed since that creation, and by comparing Long Count dates across monuments the Maya scribes could compute intervals of centuries and millennia with arithmetical precision that few ancient civilizations matched.

The basic structure of the Long Count is five nested units of days. The kin is a single day. Twenty kin make a uinal (20 days). Eighteen uinal make a tun (360 days) — the one place in the count that uses a multiplier of 18 rather than 20, because 18 x 20 = 360 approximates the solar year. Twenty tun make a katun (7,200 days, or about 19.7 solar years). Twenty katun make a baktun (144,000 days, or about 394.3 solar years). A Long Count date is written as five numbers separated by dots, from largest to smallest: baktun.katun.tun.uinal.kin. Thus 9.16.12.5.17 means 9 baktun + 16 katun + 12 tun + 5 uinal + 17 kin from the creation date — a specific day in the Classic Period reign of the Palenque ruler K'inich Kan Bahlam II, as decoded by Linda Schele and others.

The Long Count is a positional number system in base 20 (vigesimal), with the single exception of the tun-to-katun position, which uses base 18 to bring the count close to a solar year. Because the Maya scribes had developed a genuine place-value system including a zero symbol, they could write arbitrarily large numbers and could perform additions and subtractions directly on the numerical notation. The zero is conventionally rendered as a stylized shell or as a specific head-variant glyph, and its presence in Maya mathematics predates the Old World introduction of positional zero by many centuries. David Kelley's Deciphering the Maya Script (University of Texas Press, 1976) remains a foundational treatment of the Long Count notation, and Michael D. Coe and Mark Van Stone's Reading the Maya Glyphs (Thames & Hudson, 2005) is the best short introduction for new readers.

The earliest securely dated Long Count monument is Stela 2 at Chiapa de Corzo in Chiapas, which records the date 7.16.3.2.13 (36 BCE in the GMT correlation). This places the origin of the Long Count in the Late Preclassic period and in a region that was not yet Maya in the Classic sense — the Chiapa de Corzo stela belongs to the Izapan tradition, a transitional culture on the Pacific slope between the older Olmec and the later Classic Maya. Other very early Long Count monuments are Tres Zapotes Stela C (7.16.6.16.18, about 32 BCE, from the Epi-Olmec region), El Baul Stela 1 (7.19.15.7.12, about 36 CE), and the Abaj Takalik monuments. Taken together, these inscriptions show that the Long Count was invented somewhere in the Late Preclassic Isthmian zone — likely by the Epi-Olmec and related cultures — and was transmitted northward and eastward into the Maya lowlands during the Late Preclassic and Early Classic periods. By the fifth century CE, the Long Count was the standard chronological system across the Classic Maya world.

The anchor date 13.0.0.0.0 4 Ajaw 8 Kumku was treated by the Maya as the starting point of the current creation. Earlier creations were acknowledged — the Popol Vuh, the K'iche' Maya creation epic recorded in colonial times but reflecting older material, describes earlier attempts to create humanity from mud and wood that failed, before the successful creation from maize dough. The Long Count handled earlier creations by extending the count backward: the scribes at Coba and elsewhere wrote inscriptions with additional place values above the baktun — piktun, kalabtun, k'inchiltun, alawtun, and beyond — reaching back to distances on the order of 10^28 years. Coba Stela 1 famously records a date with twenty-four place values of 13, which represents a mythological starting point unimaginably distant in the past. This is not a practical chronology; it is a cosmological framing that places the 13.0.0.0.0 creation of 3114 BCE within a much larger cyclical structure.

The correlation between the Long Count and the Western calendar is called the GMT correlation after Joseph Goodman, Juan Martínez Hernández, and J. Eric S. Thompson, who established in the early twentieth century that the Julian Day Number of the creation date 13.0.0.0.0 4 Ajaw 8 Kumku is 584,283. This corresponds to 11 August 3114 BCE in the proleptic Julian calendar, or 13 August 3114 BCE in the proleptic Gregorian calendar. The GMT correlation has been tested repeatedly against astronomical, historical, and radiocarbon evidence, and while small variants (584,284 or 584,285) have been proposed, the basic GMT value is accepted by the overwhelming majority of Mayanists. Simon Martin and Nikolai Grube's work in Chronicle of the Maya Kings and Queens (Thames & Hudson, 2000, 2nd ed. 2008) uses the GMT correlation throughout and provides an accessible historical reading of Classic Maya political history based on Long Count dates.

The completion of the thirteenth baktun on 13.0.0.0.0 4 Ajaw 3 Kankin — corresponding in the GMT correlation to 21 December 2012 CE — became the basis of a wave of popular speculation in the late twentieth and early twenty-first centuries about a supposed Maya prophecy of the end of the world. This was a misreading on multiple levels. The Maya did not have a single inscription stating that the world would end on 13.0.0.0.0. The Tortuguero Monument 6 text, which references 13.0.0.0.0, describes the arrival or return of the god Bolon Yokte' K'uh and associates the date with a commemoration rather than a cataclysm. Gerardo Aldana's analyses, Stanley Guenter's translation of the Tortuguero text, and the broader work of Mayanists such as Simon Martin, David Stuart, and Anthony Aveni all agree that 2012 was understood by the Classic Maya as a major calendrical milestone — the completion of a thirteen-baktun cycle analogous to an odometer rollover — but not as a prediction of world-ending catastrophe. The continued use of the Long Count beyond 13.0.0.0.0 in some later inscriptions, and the presence of forward projections into future baktuns at sites like Palenque (where the Temple of the Inscriptions contains references to dates thousands of years in the future), further demonstrate that the Maya did not understand 13.0.0.0.0 as a terminus. Anthony Aveni's The End of Time: The Maya Mystery of 2012 (University Press of Colorado, 2009) is the most direct and readable refutation of the doomsday misreading.

The Long Count works in concert with the Tzolkin (260-day sacred count) and Haab (365-day civil calendar) to form the Calendar Round, a 52-year cycle that repeats when the same Tzolkin day and the same Haab day coincide. Every Long Count date on a Classic Maya monument is typically accompanied by its Tzolkin and Haab partners, giving four calendar coordinates at once. The Long Count supplies the linear chronology; the Tzolkin and Haab supply the ritual and seasonal signatures. Beyond these, the Supplementary Series — a group of additional glyphs that sometimes accompany a Long Count date — includes the Lunar Series (recording the age of the moon, the length of the current lunation, and the position of the moon within a six-lunation series) and other cycles. The Supplementary Series, decoded progressively by John Teeple, Linton Satterthwaite, and later Floyd Lounsbury and others, shows that the Classic Maya integrated their Long Count with careful lunar observation and with at least a partial eclipse-prediction framework.

The Long Count also served a political function. Rulers commissioned stelae and altars with Long Count dates to commemorate accession, warfare, marriage, birth, death, ritual period-endings (especially katun and half-katun endings), and the dedications of temples and ball courts. The period-ending ceremonies — when the Long Count rolled over from one katun to the next, or from one tun to the next — were particularly important ritual occasions, marked by scattering rituals, bloodletting, and the erection of new monuments. Linda Schele and David Freidel's A Forest of Kings (William Morrow, 1990) and Simon Martin and Nikolai Grube's Chronicle of the Maya Kings and Queens reconstruct much of Classic Maya political history from such inscriptions, using the Long Count as the chronological spine.

The Long Count essentially disappeared from use after the Terminal Classic collapse (c. 900 CE) in the southern lowlands. Postclassic Maya at Chichen Itza, Mayapan, and elsewhere used a Short Count — a cycle of thirteen katuns of unequal length — rather than the full Long Count. The last securely dated Long Count inscription is Tonina Monument 101 at 10.4.0.0.0 (909 CE), though there are a few later or ambiguous examples. The decline of the Long Count tracks the Classic Maya political collapse, but the Tzolkin, Haab, and Calendar Round continued in use into the colonial period and in some highland communities into the present day, where they survive as living ritual calendars maintained by day-keepers.

Purpose

The Long Count served multiple purposes in Classic Maya civilization, and the purposes shifted as the calendar matured from its Late Preclassic Isthmian origins to its full Classic Maya development. The proximate purpose was chronological: the Long Count gave Maya scribes a way to specify any day uniquely, without ambiguity. The Tzolkin and Haab alone cannot do this, because the Calendar Round repeats every 52 years — a date expressed only in Tzolkin and Haab terms will recur within a single human lifetime and cannot distinguish, say, the accession of one ruler from that of a grandfather who acceded fifty-two years earlier. The Long Count eliminates this ambiguity by anchoring every date to a fixed creation point, and this chronological precision is essential for a dynastic culture that cared about recording history in stone.

A second purpose was ritual. The period-endings of the Long Count — the completions of tun, half-katun, katun, and occasionally larger units — were major ritual occasions in Classic Maya religion. The rulers of Tikal, Copan, Quirigua, Yaxchilan, and elsewhere marked these endings by erecting stelae, performing bloodletting rituals, scattering offerings, and performing dances and processions. The evidence is in the stelae themselves, which overwhelmingly cluster on katun and half-katun endings. The Long Count thus was not just a chronological device but a ritual calendar of recurring moments that the political and religious establishment observed systematically. Linda Schele and Mary Ellen Miller, in The Blood of Kings (Kimbell Art Museum, 1986), documented the ritual programs associated with Long Count period-endings in detail.

A third purpose was astronomical. The Long Count's fixed-length units — particularly the tun of 360 days — allowed the Maya to build internally consistent tables of planetary and lunar cycles. The Venus Table of the Dresden Codex, for example, operates on a base of 2,920 days (equal to 5 synodic Venus periods of 584 days), and this base is related by arithmetical manipulation to the tun and the haab. The lunar series attached to Long Count dates in the Classic Period inscriptions records the age of the moon and the position within a six-month lunation count, allowing the scribes to interpolate between observations. The eclipse tables in the Dresden Codex use interval additions on Long Count dates. Floyd Lounsbury's work on the Venus Table, published in the Cambridge Encyclopedia of Astronomy and in various journal articles, showed how the Long Count arithmetic meshes with the Venus synodic period through deliberate correction factors.

A fourth purpose was cosmological. The mythological creation date 13.0.0.0.0 4 Ajaw 8 Kumku, and the extended Long Count dates at Coba and elsewhere with their enormous place values, frame Classic Maya historical time within a much larger cyclical cosmology. The current creation, which began on 13 August 3114 BCE, was understood as one of several that the gods had performed, and earlier creations could be referenced by extending the count backward. The cosmological function of the Long Count was to place the present ruler, the present dynasty, and the present ritual moment within a framework of deep time that made them meaningful. David Stuart's work on the cosmological inscriptions at Palenque, particularly those that refer to events at the beginning of the current creation, shows how the ruling dynasty used the Long Count to connect their present-day rituals to the events of the mythological past.

A fifth purpose, visible only in later retrospect, was the construction of a historical record that could survive the death of the ruler who commissioned it. Classic Maya stelae are permanent monuments, often carved on durable limestone or sandstone, designed to outlast any individual lifetime. By placing a Long Count date on a stela, the scribes ensured that any later reader — whether a successor king, a rival polity, or a modern archaeologist — could place the event on an absolute timeline. The Long Count was the Classic Maya's way of speaking to posterity. It was not just a record-keeping tool; it was an assertion that the ritual and political actions of the present would echo forward in time.

A sixth purpose was the integration of political and cosmic calendars. When a Classic Maya ruler performed a katun-ending ceremony, the ritual meaning derived from the coincidence of the political event (the ruler's accession or reign year) with the cosmic event (the completion of a katun cycle). The Long Count made such integration possible by providing a unique label for every day that tied ritual to cosmology. This is one reason period-ending ceremonies were so important: they were moments when the political present aligned with the deep cosmic structure of time.

Precision

The Long Count itself is not a measurement and therefore has no observational precision in the usual sense. It is an arithmetical day-count, and its precision is the precision of counting — each kin is exactly one day, each tun is exactly 360 days, each baktun is exactly 144,000 days, by definition. The interesting questions about precision concern not the Long Count itself but its interaction with astronomical cycles and the calibration between the Long Count and the Western calendar.

The tun of 360 days is notably not the solar year. The true tropical year is approximately 365.2422 days, so a tun runs about 5.2422 days shorter than the solar year. The Maya were aware of this discrepancy. The Haab of 365 days is closer to the tropical year but still differs by about 0.2422 days per year, accumulating to about a day every four years. The Maya did not insert leap days into the Haab — it was a 365-day wandering year, shifting by a day every four years relative to the tropical year and by a full cycle every 1,508 Haab years. But the Maya compensated arithmetically in their astronomical tables. The Dresden Codex Venus Table, for example, contains correction factors that adjust the predicted Venus positions to match observation, implying that the scribes were tracking the discrepancy between their arithmetical model and the actual sky. Floyd Lounsbury's analysis of these corrections showed that the Maya Venus calculations are accurate to within a few days over centuries of projection.

The correlation between the Long Count and the Western calendar — the GMT correlation of 584,283 — has been tested against multiple independent lines of evidence. First, historical evidence: the conquest-era Maya of Yucatan used a modified Calendar Round that Spanish chroniclers recorded, and these records can be cross-checked against the Long Count. Second, astronomical evidence: Long Count dates on Classic Maya inscriptions are sometimes accompanied by lunar phases, Venus positions, or eclipse references, and these can be compared to modern astronomical retrocalculations. Third, radiocarbon evidence: Classic Maya sites have been dated by radiocarbon, and the resulting dates correlate with the Long Count dates on inscriptions through the GMT correlation within expected error margins. All three lines of evidence converge on the 584,283 value (or, with a one-day refinement, 584,285). Prudence Rice's Maya Calendar Origins (University of Texas Press, 2007) discusses the correlation evidence in detail.

The precision of the Long Count as a historical instrument depends on the quality of the surviving inscriptions. Many Maya stelae have suffered erosion, damage, or deliberate defacement, and not every Long Count date is legible in full. Where the full five-place Long Count is preserved, the date is unambiguous to the day. Where one or more positions are damaged, the date can often still be reconstructed from the accompanying Tzolkin and Haab coordinates, because only one combination of Long Count with those Calendar Round values fits within the plausible historical range. This cross-checking is a powerful feature of the Maya system and lets scholars recover many dates that would otherwise be lost.

The astronomical content of Long Count inscriptions — particularly the lunar series — has been tested against modern retrocalculations with generally good agreement. The lunar ages recorded in the Supplementary Series of Classic Maya inscriptions match modern lunar phases within about one day in most cases, confirming that the Maya observed the moon carefully and that the Long Count dates are accurate. Where discrepancies appear, they are usually within the noise of observational astronomy rather than systematic errors in the Long Count. The eclipse tables in the Dresden Codex predict eclipse possibilities on dates that correspond (when translated through the Long Count and the GMT correlation) to actual historical eclipses. These correspondences are detailed in Harvey and Victoria Bricker's Astronomy in the Maya Codices.

The precision of the extended Long Count — with its piktun, kalabtun, and higher positions — is purely arithmetical and has no observational content. The extended counts at Coba that reach to twenty-four place values of 13 are cosmological rather than chronological statements. They express the Maya conception of enormously deep time, not a measurement of anything. As arithmetic, they are exact; as physics or astronomy, they are not intended to correspond to any observable phenomenon.

Finally, the precision of the Long Count in modern chronology is limited by the GMT correlation constant itself. If the correlation is 584,283, then 13.0.0.0.0 4 Ajaw 8 Kumku corresponds to 13 August 3114 BCE (proleptic Gregorian). If the correlation is 584,285 (the two-day adjustment sometimes proposed), the creation date shifts by two days. These small variations do not affect the internal precision of the Long Count or the relative sequencing of Classic Maya events, but they do affect the absolute dates we assign to the inscriptions in the Western calendar. For nearly all scholarly purposes, the 584,283 GMT value is used, and the resulting absolute dates are accurate within a few days even across the entire Classic Period.

Modern Verification

Modern verification of the Long Count has proceeded through decipherment, astronomical cross-checking, radiocarbon calibration, and comparative analysis. Each of these lines of evidence has independently supported the Long Count's structure, the GMT correlation, and the interpretation of specific inscriptions.

Decipherment came first. The basic arithmetic of the Long Count was understood from the early twentieth century through the work of Joseph Goodman, Sylvanus Morley, and J. Eric S. Thompson, among others. Thompson's Maya Hieroglyphic Writing: An Introduction (Carnegie Institution, 1950, reprinted University of Oklahoma Press) was for decades the standard reference, though Thompson's own reluctance to accept a phonetic component to the writing slowed the full decipherment of the non-calendrical glyphs. The breakthrough on the phonetic side came from Yuri Knorozov in the 1950s and 1960s, and then from Linda Schele, Peter Mathews, David Stuart, and others in the 1970s and 1980s. By the 1990s, the structure of the Long Count was fully understood, the dynasties of the major Classic Maya polities had been reconstructed, and the ritual and political meanings of period-ending inscriptions were being decoded.

Astronomical cross-checking has been particularly effective. The Dresden Codex Venus Table was analyzed by Floyd Lounsbury in a series of papers (including "The Base of the Venus Table of the Dresden Codex, and Its Significance for the Calendar-Correlation Problem," in Calendars in Mesoamerica and Peru, ed. Anthony Aveni and Gordon Brotherston, BAR International Series 174, 1983), and the Long Count dates in the table correspond, through the GMT correlation, to actual Venus heliacal risings within observational error. The lunar series on Classic Maya stelae correspond to actual lunar phases within about a day. Eclipse references in the Dresden Codex correspond to actual eclipse possibilities. Anthony Aveni's Skywatchers (originally Skywatchers of Ancient Mexico, University of Texas Press, 1980, revised edition 2001) covers these astronomical cross-checks in detail and remains the standard treatment.

Radiocarbon calibration has provided independent support for the GMT correlation. Classic Maya sites have been dated by radiocarbon analysis of wooden beams, charcoal from hearths, and other organic materials, and the resulting dates are consistent with the Long Count chronology derived from the GMT correlation. Tikal, Copan, Palenque, Piedras Negras, and many other sites have been extensively dated, and the radiocarbon dates overlap with the Long Count dates within expected error margins. This independent verification from a completely different methodology is one of the strongest arguments for the GMT correlation.

The 2012 phenomenon — the popular belief that the Maya had predicted the end of the world on 21 December 2012 — provided an opportunity for modern Mayanists to communicate what the Long Count says and what it does not. The response was robust and largely unified. Anthony Aveni's The End of Time (University Press of Colorado, 2009), David Stuart's The Order of Days: The Maya World and the Truth About 2012 (Harmony, 2011), Mark Van Stone's 2012: Science and Prophecy of the Ancient Maya (Tlacaelel Press, 2010), and papers by Gerardo Aldana and others all made the same basic points: there is no Maya prophecy of world-ending catastrophe, the Tortuguero text describes a ritual commemoration, Classic Maya inscriptions at Palenque and elsewhere reference dates thousands of years in the future, and the Long Count was expected to continue past 13.0.0.0.0. The collective scholarly response to 2012 is a case study in how academic archaeology can respond to popular misinterpretation.

Gerardo Aldana's work in particular, including Calculating Brilliance: An Intellectual History of Mayan Astronomy (University of Arizona Press, 2016), has explored how Maya astronomical and mathematical knowledge interacted with political and ritual practice, using the Long Count as the primary framework. Aldana's detailed reconstructions of how Maya scribes used the Long Count in astronomical calculation have clarified many points that earlier scholars had only partially understood.

The extended Long Count dates at Coba and elsewhere have been analyzed by Simon Martin and others, who have shown that they are arithmetically consistent and that they reflect a genuine Maya cosmological interest in deep time. The extended dates do not represent observational claims but rather a cosmological framing in which historical time is placed within a vast cyclical structure.

Finally, the continued use of elements of the Maya calendrical system in living highland Maya communities — where day-keepers still maintain the Tzolkin and perform rituals on particular day-sign and number combinations — provides a form of living verification. While the Long Count itself is not in daily use in these communities, the Calendar Round and the associated ritual practices are, and they connect directly to the Classic Period system. Barbara Tedlock's Time and the Highland Maya (University of New Mexico Press, 1982, revised 1992) is the classic ethnographic treatment of the surviving calendar tradition among the K'iche' of Momostenango.

Significance

The Long Count is significant along several distinct dimensions — mathematical, chronological, astronomical, historical, and comparative — and each dimension deserves its own treatment.

Mathematically, the Long Count is one of the clearest demonstrations that Maya civilization developed a true positional number system with a functional zero. The Maya are the only ancient civilization in the Americas, and one of very few in world history, to have invented positional zero independently. The Babylonians developed a placeholder zero but did not consistently use it in terminal positions. Indian mathematicians developed positional zero in the late first millennium CE, and from India it reached the Islamic world and then Europe. The Maya zero, attested on Long Count monuments from at least the first century BCE, is earlier than the Indian development by several centuries and appears to be entirely independent. This alone would make the Long Count a landmark in the history of mathematics.

Chronologically, the Long Count gives us direct access to the political and ritual history of the Classic Maya in a way that no other ancient New World civilization allows. The Long Count dates on stelae can be cross-checked against lunar data, Venus data, and the Calendar Round, and the resulting chronology is secure to within a day across centuries. This means that when Linda Schele decoded the dynastic history of Palenque, or when Simon Martin and Nikolai Grube worked out the political rivalries between Tikal and Calakmul, they could place events on an absolute timeline — the accession of Pakal the Great at Palenque on 9.9.2.4.8 (27 July 615 CE), his death on 9.12.11.5.18 (29 August 683 CE), the burial rituals that followed, and so on. No other pre-Columbian civilization supports this level of chronological resolution.

Astronomically, the Long Count is the scaffolding on which the Maya hung their lunar, solar, Venus, and eclipse calculations. The Supplementary Series glyphs attached to Long Count dates give lunar age, lunation length, and the position within a six-month lunar count; the Dresden Codex Venus Table (discussed in the Venus cycle entry) presupposes a Long Count framework; the eclipse tables in the Dresden Codex and elsewhere operate through interval additions on Long Count dates. Without the Long Count, the astronomical achievements of the Dresden Codex would not be securely datable or internally coherent. Harvey and Victoria Bricker's work, particularly Astronomy in the Maya Codices (American Philosophical Society, 2011), is the standard modern treatment of how Long Count arithmetic underlies the Dresden and Madrid astronomical tables.

Historically, the Long Count gives us the best-documented political history in the pre-Columbian Americas. The decipherment of Maya writing by Yuri Knorozov, Linda Schele, David Stuart, and others during the second half of the twentieth century transformed Maya studies from an archaeology of anonymous sites into a history of named rulers, dynastic conflicts, wars, marriages, and ritual programs. Every one of these reconstructions rests on the Long Count dating framework. The names and political careers of Yax K'uk' Mo' at Copan, Jasaw Chan K'awiil at Tikal, K'ak' Tiliw Chan Yopaat at Quirigua, the various rulers of the Kaanul (Snake) dynasty at Calakmul, and others, are known only because the Long Count lets us sequence their stelae and match them to the events described in the hieroglyphic texts.

Comparatively, the Long Count is valuable because it is the only fully documented ancient day-count calendar from the Americas and one of very few from anywhere in the world. The Egyptian civil calendar counted days in wandering years. The Babylonian calendar counted days and lunations within a complex lunisolar framework. The Roman Julian calendar and its successors count days in a fixed solar year. But the Maya Long Count is unusual in that it counts days linearly from a fixed origin, without recycling and without reference to a solar or lunar base cycle. This makes it much more like the Julian Day Number used by modern astronomers — a linear day count from an arbitrary origin — than like any other ancient civil calendar. The fact that the Maya independently invented this kind of linear day-count system is historically remarkable.

Finally, the Long Count matters because of its misuse. The 2012 phenomenon was a significant episode in the modern reception of Maya culture, and the scholarly response to it — from Anthony Aveni, Gerardo Aldana, David Stuart, Simon Martin, and many others — is an important case study in how academic knowledge interacts with popular speculation. The Maya did not predict the end of the world. They built a calendar whose largest commonly used cycle completed in 2012, and they expected the calendar to continue. The significance of this point, and the care with which it has been explained, is itself a significant episode in the public history of archaeoastronomy.

Connections

The Long Count anchors the chronology of Classic Maya civilization and interlocks with several other calendrical, astronomical, and cultural systems that each have their own entries. The most immediate connection is to the Tzolkin 260-day sacred calendar, the ritual count that accompanies every Long Count date on a Classic Maya inscription. The Tzolkin entry covers the 20 day-signs and 13 numbers, the debates about why 260 days, and the ritual use of the sacred count both in Classic times and in modern highland Maya communities.

Equally important is the Haab 365-day civil calendar, the agricultural year of 18 twenty-day uinal plus the five-day Wayeb. The Haab entry covers the structure of the civil year, its relationship to the solar year (and the absence of a leap-year correction), and the Calendar Round that results from the coincidence of Tzolkin and Haab. The Long Count, Tzolkin, and Haab together form the full Classic Maya calendrical system, and understanding any one of them requires understanding the others.

For the astronomical content that the Long Count frames, see the Venus cycle in Mesoamerican astronomy, which covers the Dresden Codex Venus Table, the 584-day synodic period, and the ritual and divinatory significance of Venus to the Classic Maya. The Venus Table uses Long Count arithmetic throughout and cannot be understood without it.

For the political and cultural civilization that produced the Long Count, see the Maya civilization more broadly. That entry covers the Classic Period polities — Tikal, Calakmul, Palenque, Copan, Quirigua, Yaxchilan, Piedras Negras — and the dynastic history that the Long Count makes accessible to us. For the earlier civilization that contributed to the development of the Long Count, see the Olmec, whose Late Preclassic descendants in the Isthmian zone appear to have invented the Long Count before it was adopted by the Classic Maya.

For major sites where Long Count inscriptions are especially important, see Chichen Itza, where the Postclassic successor calendar (the Short Count) replaced the full Long Count but where earlier inscriptions still preserve Long Count dates, and Palenque, the Classic Period city whose Temple of the Inscriptions contains some of the most elaborate Long Count dating programs, including forward projections thousands of years into the future that definitively refute any "end of time" reading of the 13.0.0.0.0 cycle ending.

Further Reading

• Aveni, Anthony F. Skywatchers: A Revised and Updated Version of Skywatchers of Ancient Mexico. University of Texas Press, 2001 (revised edition of 1980 original). Standard treatment of Mesoamerican archaeoastronomy, including the Long Count and its astronomical content.
• Aveni, Anthony F. The End of Time: The Maya Mystery of 2012. University Press of Colorado, 2009. The most direct scholarly refutation of the 2012 doomsday misreading of the Long Count.
• Stuart, David. The Order of Days: The Maya World and the Truth About 2012. Harmony, 2011. Accessible treatment by one of the foremost living Mayanists; includes detailed discussion of the Tortuguero Monument 6 text.
• Kelley, David H. Deciphering the Maya Script. University of Texas Press, 1976. Foundational treatment of the Long Count notation and Maya writing more broadly.
• Coe, Michael D., and Mark Van Stone. Reading the Maya Glyphs. 2nd ed., Thames & Hudson, 2005. The best short introduction to Maya hieroglyphic writing, including Long Count dates.
• Martin, Simon, and Nikolai Grube. Chronicle of the Maya Kings and Queens: Deciphering the Dynasties of the Ancient Maya. 2nd ed., Thames & Hudson, 2008. Standard reference for Classic Maya political history, built on Long Count chronology.
• Rice, Prudence M. Maya Calendar Origins: Monuments, Mythistory, and the Materialization of Time. University of Texas Press, 2007. Detailed treatment of the Late Preclassic origins of the Long Count.
• Bricker, Harvey M., and Victoria R. Bricker. Astronomy in the Maya Codices. American Philosophical Society, 2011. Definitive treatment of the astronomical content of the Dresden and Madrid codices, all framed by Long Count arithmetic.
• Aldana, Gerardo. Calculating Brilliance: An Intellectual History of Mayan Astronomy at Chich'en Itza. University of Arizona Press, 2016. Advanced treatment of how Maya astronomers used the Long Count in computation.
• Tedlock, Barbara. Time and the Highland Maya. Revised edition, University of New Mexico Press, 1992. Ethnographic account of living Maya calendrical practice.
• Schele, Linda, and David Freidel. A Forest of Kings: The Untold Story of the Ancient Maya. William Morrow, 1990. Narrative history of Classic Maya politics built from Long Count-dated inscriptions.
• Thompson, J. Eric S. Maya Hieroglyphic Writing: An Introduction. 3rd ed., University of Oklahoma Press, 1971. Classic older reference; dated on phonetic decipherment but still useful for the calendar.