Mayan Calendar Converter
Enter any date in the Gregorian calendar to see it expressed in the three interlocking Maya calendar systems: the Long Count (the 5,125-year chronological count), the 260-day Tzolk'in ritual cycle, and the 365-day Haab' agricultural year. You also get the Lord of the Night from the nine-deity cycle. To convert a Long Count date back to Gregorian, switch to Reverse mode.
The three interlocking Maya calendar systems
The ancient Maya used three main calendar systems simultaneously, each serving a different purpose. The Long Count is a linear count of days from a fixed creation date (August 11, 3114 BCE in the Gregorian calendar, using the GMT correlation constant of 584,283). It is written as five numbers separated by periods: b'ak'tun.k'atun.tun.winal.k'in, where each unit is 20 times the next smaller one, except the tun which is 18 winals (360 days). The Tzolk'in is a 260-day ritual cycle formed by pairing a number from 1 to 13 with one of 20 named days, producing 260 unique combinations used for divination and ceremony. The Haab' is a 365-day solar approximation divided into 18 months of 20 days each plus a 5-day period called Wayeb' at the year's end. The Tzolk'in and Haab' mesh together like interlocking gears, and any given combination of the two recurs only every 52 Haab' years (18,980 days), a period known as the Calendar Round.
How the GMT correlation works
To convert between the Gregorian calendar and the Maya Long Count, scholars use a correlation constant that links the two systems by identifying which Julian Day Number (JDN) corresponds to the Maya epoch 0.0.0.0.0. The most widely accepted constant is 584,283, derived by Goodman, Martinez, and Thompson (the GMT correlation). This places the Maya creation date at August 11, 3114 BCE (Julian Day Number 584,283). To find the Maya day count for any date, you first convert the Gregorian date to its JDN using the standard astronomical formula, then subtract 584,283. The Long Count components are extracted by successive division: dividing by 144,000 gives the b'ak'tun, then dividing the remainder by 7,200 for the k'atun, 360 for the tun, 20 for the winal, with the final remainder being the k'in.
The Long Count and the 2012 phenomenon
The Long Count date 13.0.0.0.0 fell on December 21, 2012, which marks the completion of the 13th b'ak'tun cycle - a period of 1,872,000 days or approximately 5,125.36 years. Popular culture linked this to supposed Maya prophecies of catastrophe, but Mayanist scholars universally rejected this interpretation. Maya inscriptions actually describe dates beyond the 13th b'ak'tun (the 14th through 19th and even further), and the completion of a b'ak'tun cycle was a cause for celebration, not apocalypse, in classical Maya society. The date that follows 13.0.0.0.0 in the inscriptions is 13.0.0.0.1, just as a new year follows December 31.
Tzolk'in and Haab' in practice
Every Maya child received a Tzolk'in name based on their birth date, and the day sign carried meaning about personality and destiny. Priests known as daykeepers still use the Tzolk'in calendar in highland Guatemala today, having maintained an unbroken count since antiquity. The Haab', with its 18 named months, aligned roughly with the solar year though without a leap day correction, so it slowly drifted relative to the tropical year over centuries. Important ceremonies were often tied to the Haab' month position. The five-day Wayeb' period that closes the Haab' year was considered unlucky, a liminal time when the boundaries between worlds were thin and normal activity was dangerous.
Tzolk'in day names and Haab' months
| Position | Tzolk'in day name | Haab' month |
|---|---|---|
| 1 | Imix | Pop |
| 2 | Ik' | Wo' |
| 3 | Ak'b'al | Sip |
| 4 | K'an | Sotz' |
| 5 | Chikchan | Sek |
| 6 | Kimi | Xul |
| 7 | Manik' | Yaxk'in' |
| 8 | Lamat | Mol |
| 9 | Muluk | Ch'en |
| 10 | Ok | Yax |
| 11 | Chuwen | Sak' |
| 12 | Eb' | Keh |
| 13 | B'en | Mak |
| 14 | Ix | K'ank'in |
| 15 | Men | Muwan' |
| 16 | K'ib' | Pax |
| 17 | Kab'an | K'ayab' |
| 18 | Etz'nab' | Kumk'u |
| 19 | Kawak | Wayeb' (5 days) |
| 20 | Ajaw | - |
All 20 Tzolk'in day names and all 19 Haab' periods (18 months of 20 days + 5-day Wayeb').
Frequently asked questions
What is the GMT correlation constant and why does it matter?
The GMT correlation constant (584,283) is the Julian Day Number assigned to the Maya epoch 0.0.0.0.0. It was established by combining the independent research of Joseph Goodman, Juan Martinez, and Sir John Eric Thompson. Without a correlation constant, it would be impossible to anchor the Long Count to the Gregorian or Julian calendar. The constant 584,283 is accepted by the vast majority of epigraphers and archaeoastronomers based on historical documents, astronomical events recorded in Maya inscriptions, and radiocarbon dating of associated materials.
What happened on December 21, 2012?
The Long Count reached 13.0.0.0.0, completing the 13th b'ak'tun cycle (1,872,000 days since the Maya creation date). Contrary to popular accounts, Maya inscriptions do not describe this as the end of the world. Epigraphers found texts referring to dates well beyond 2012, and classical Maya celebrations of period endings were occasions for renewal, not destruction. The date is genuinely significant in Maya cosmology as a grand cycle completion, but it was a new beginning, not a terminus.
Can I convert BCE dates?
Yes. Enter a negative year number for BCE dates. Note that the astronomical year convention used here treats year 0 as 1 BCE, year -1 as 2 BCE, and so on (the proleptic Gregorian calendar). The Maya epoch itself falls in 3114 BCE (astronomical year -3113). Dates before the Maya epoch (0.0.0.0.0) cannot be expressed as Long Count dates since the count had not yet started.
What are the Lords of the Night?
The nine Lords of the Night (sometimes called the G series: G1 through G9) are nine deities that cycle through successive days in an unbroken sequence. They appear in Maya inscriptions, often as a glyph labeled G followed by a number. Their specific identities and mythology vary by region and period, but they were associated with the underworld and nighttime. Each Long Count date is accompanied by its Lord of the Night, giving additional ritual context to the day.
What is the Calendar Round?
The Calendar Round is the combined position in both the Tzolk'in and the Haab'. Because 260 and 365 share a greatest common divisor of 5, it takes 260 x 365 / 5 = 18,980 days (about 52 Haab' years) for any given Tzolk'in-Haab' combination to recur. The Maya used the Calendar Round date as a common way to identify a day in everyday contexts, though for historical records spanning more than 52 years, the Long Count was necessary to distinguish repetitions.