Convert Gregorian dates to Mayan Long Count, Tzolk'in & Haab' — and back
Instantly see today's date expressed in the Mayan Long Count calendar, Tzolk'in sacred calendar, and Haab' civil calendar.
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The Mayan Long Count calendar was developed around 36 BCE (though some inscriptions date to 400 BCE) and was used across Mesoamerica by the Maya, Olmec, and other civilizations. It counts forward from a mythological creation date corresponding to August 11, 3114 BCE in the proleptic Gregorian calendar (the GMT correlation). The system counts individual days (K'in) in a vigesimal (base-20) progression, with the sole exception of the Uinal period (18 × 20 = 360 days), designed to approximate the solar year. The famous 13th Bak'tun ended on December 21, 2012 CE — the completion of one Great Cycle of 5,125.36 years — an event misinterpreted by modern popular culture but celebrated by contemporary Maya communities as a renewal, not an apocalypse.
This tool offers three conversion modes. In Gregorian → Mayan mode, pick any date and instantly see its Long Count notation, Tzolk'in day name (from the 260-day sacred cycle), and Haab' month position (from the 365-day civil calendar). In Mayan → Gregorian mode, enter a Long Count date (such as 9.16.4.1.1 for a famous stele inscription) and recover the equivalent Gregorian date. The Today tab shows the current date in all three Mayan calendar systems simultaneously.
The Mayan calendar system is one of humanity's greatest intellectual achievements. Unlike the Gregorian calendar — which simply counts years from a religious milestone — the Long Count is an absolute positional system capable of expressing any date across millions of years with perfect precision.
Historians and archaeologists rely on Long Count dates inscribed on stelae, altars, and codices to anchor Mayan events in real time. For example, the accession of King Pakal of Palenque on 9.9.2.4.8 (July 29, 615 CE) and his death on 9.12.11.5.18 (August 28, 683 CE) are known with absolute certainty because of Long Count inscriptions. Without this calendar, Mayan chronology would be nearly impossible to reconstruct. The calendar also underpins sophisticated astronomical calculations — the Venus Table in the Dresden Codex uses the 584-day Venus cycle interlocked with the 260-day Tzolk'in to make predictions accurate to within 2 hours over 481 years.
The conversion uses the GMT correlation constant (584,283 Julian Day Number), the most widely accepted scholarly correlation linking the Mayan and Gregorian calendars.
The Uinal counts only 0–17 (not 0–19) so that 18 Uinals × 20 K'in = 360 days = 1 Tun, approximating the solar year. All other positions use base 20.
The Long Count is an absolute positional calendar system used by the ancient Maya to record historical and mythological events. It counts days from a fixed creation date (August 11, 3114 BCE in the Gregorian calendar) in units of K'in (1 day), Uinal (20 days), Tun (360 days), K'atun (7,200 days), and Bak'tun (144,000 days). It's the Mayan equivalent of a Julian Day Number — a single, unambiguous count of elapsed days.
No. The date marked the end of the 13th Bak'tun (13.0.0.0.0), completing one "Great Cycle" of 5,125.36 solar years — a significant calendrical milestone, not a prophecy of destruction. Contemporary Maya scholars and indigenous Maya leaders were unanimous: the date was a moment for renewal and celebration, not apocalypse. The "2012 phenomenon" was a largely Western pop-culture invention with no basis in actual Mayan texts.
The Tzolk'in is a 260-day sacred calendar combining 13 numbered day signs with 20 named day signs (e.g., 4 Ajaw). It was used for divination, ritual scheduling, and naming children. The Haab' is a 365-day civil calendar of 18 months of 20 days each, plus a 5-day "Wayeb'" period considered unlucky. Together they form the 52-year Calendar Round — the "century" of Mesoamerican civilization.
The GMT correlation (named after scholars Goodman, Martínez, and Thompson) is the number 584,283 — the Julian Day Number corresponding to the Mayan Long Count creation date 0.0.0.0.0. It's the "Rosetta Stone" linking Mayan dates to the Western calendar and is supported by astronomical back-calculations, colonial-era documents, and living Maya tradition. This tool uses the 584,283 constant, which is the current scholarly consensus.