Calendars

Haab

Solar

Citation Formats

General Reference

Divinity Atlas. "Haab." Accessed August 30, 2026. https://divinity.interactivelion.com/calendars/haab.

APA Style

Divinity Atlas. (n.d.). Haab. Retrieved August 30, 2026, from https://divinity.interactivelion.com/calendars/haab

BibTeX

@misc{divinityatlas-haab,
  author = {Divinity Atlas},
  title = {Haab},
  year = {2026},
  url = {https://divinity.interactivelion.com/calendars/haab},
  note = {Accessed August 30, 2026}
}

Origin The 365 day Haab, eighteen twenty day months plus the five day Wayeb, is attested in Maya inscriptions from the Late Preclassic period, with securely dated examples from around the first century BCE, and remained in continuous use through the Postclassic period into the early Spanish colonial era.

The Haab is the Maya 365 day count, made of eighteen named months of twenty days each followed by five unlucky days called Wayeb, an arrangement it shares with the Aztec Xiuhpohualli. It carries no leap correction, so it drifts slowly against the true solar year rather than tracking it exactly. Meshed with the 260 day Tzolkin it produces the Calendar Round, the fifty two year cycle in which a given pairing of Haab and Tzolkin dates returns only once; the two counts interlock but are not the same thing, and Long Count inscriptions typically give both positions together.

Facts

Origins

Historical Origin

Attested already in the Classic Maya period alongside the Tzolkin and the Long Count, recorded together in monumental inscriptions and the surviving bark paper codices. 1

Origin Period

The 365 day Haab, eighteen twenty day months plus the five day Wayeb, is attested in Maya inscriptions from the Late Preclassic period, with securely dated examples from around the first century BCE, and remained in continuous use through the Postclassic period into the early Spanish colonial era. 1

Place of Origin

The Maya lowlands of the Yucatan Peninsula and adjacent parts of Mesoamerica. 1

Origin of the Name

Haab is the Yucatec Mayan word for year. 1

Attributions

Epoch

Carries no epoch year of its own. It is a 365 day count with no leap correction and no era, meshed with the Tzolkin to produce the Calendar Round rather than counted from a fixed starting date. 1

Year Length

365 days, with no leap correction 1

Calendar Type

Count 1

Associated Religion

Maya religion 1

Reckoning

Repeating Cycle

365 1

Structure

Eighteen named months of twenty days followed by Wayeb, a remainder of five days held to be unlucky, 365 days in all. There is no leap day, so the count slips against the true solar year by about a quarter of a day each year. 1

Status

Status Today

Living tradition, practised today 1

Contemporary Maya daykeepers keep the 260 day Tzolkin more actively for ceremonial purposes; the Haab persists mainly through farmers using it to time planting and harvest offerings, and general community life has largely folded its year into the Catholic liturgical calendar.

Learn More

Eighteen Months of Twenty, and Five Days Over

The arithmetic is deliberate rather than awkward. Eighteen periods of twenty days give three hundred and sixty, a figure that fits the vigesimal counting used throughout Mesoamerican mathematics, and the remaining five days are appended as a separate short period at the end. Those five stand outside the regular structure and were treated as a dangerous interval, a time for restraint rather than for undertaking anything. The way dates are written inside a month is worth noting because it surprises modern readers.

Positions are counted from a seating of the month, so the first day of a period is its seating and the numbering of ordinary days runs from there to nineteen before the next seating arrives. A date therefore states that so many days of a named period have elapsed, rather than naming the day directly. The same eighteen and five arrangement appears across Mesoamerica with different month names, including in the Aztec year count, which indicates a shared inheritance rather than parallel invention. What differs between systems is where the year begins and how the five day period is treated, and those differences are among the sharpest markers of which tradition a given inscription or document belongs to.

No Leap Day, and That Was Not an Oversight

The count contains no correction for the quarter day by which the solar year exceeds three hundred and sixty five, so it slips against the seasons at roughly one day every four years, and a given month arrives about a month earlier in the seasons every century and a bit. Mesoamerican astronomers were entirely capable of measuring the discrepancy, so the absence of a correction is a design decision rather than an error. The reason is that this count was not carrying the burden of tracking the sun.

Long Count notation supplied an absolute day tally that anchored everything, seasonal and agricultural timing could be observed directly, and the meshing of this count with the two hundred and sixty day cycle produced a fifty two year period whose integrity depends on both counts running without adjustment. Inserting a leap day would break the meshing, which is the thing the system exists to do. Whether any community ever applied a correction has been debated, with arguments made from month names that appear to have drifted out of their seasons and from colonial period records. No agreed evidence of a systematic adjustment has been produced, and the atlas records the count as uncorrected while noting that the question has been raised seriously.

Cross-Tradition Connections