Mayan and Aztec Day Sign Calculator

Convert any date into the 260-day sacred calendar shared by the Maya and the Aztecs: your day number and sign, the Haab' solar date, the Long Count and the Aztec equivalent.

For entertainment and self-reflection: The calendar conversion follows the scholarly GMT correlation; the personality associations are modern interpretations of the day signs. Nothing on this page is a prediction, and it is not financial, medical, psychological or legal advice. Use it as a prompt for thought, not as a basis for decisions.

How the conversion works

The Maya and their neighbours across Mesoamerica ran several calendars at once, like interlocking gears. The best known is the 260-day ritual count, called the Tzolk'in by modern Maya scholars and the tonalpohualli ("count of days") in Nahuatl, the language of the Aztecs. It pairs a number from 1 to 13 with one of 20 named days. Both advance together each day, so 1 Imix is followed by 2 Ik', 3 Ak'bal and so on; after 13 the numbers start again at 1 while the names keep going, and the same combination only returns after 13 × 20 = 260 days.

To turn a modern date into a Maya date, the calculator first converts it into a Julian Day Number, a running count of days used by astronomers. Before October 15, 1582 it uses the Julian calendar, as historians do, and after that the Gregorian calendar. It then subtracts 584,283, the "GMT correlation" named after Goodman, Martínez Hernández and Thompson, which is the value accepted by most Maya scholars and supported by radiocarbon and astronomical evidence. That gives the number of days since the Maya creation date of 13.0.0.0.0, 4 Ajaw 8 Kumk'u, which falls on August 11, 3114 BC in the proleptic Gregorian calendar. From there it is simple remainder arithmetic: the day number repeats every 13, the day name every 20, the Haab' every 365, and the Lords of the Night every 9.

We checked the engine against the anchor dates every Maya calendar programme must hit. December 21, 2012 comes out as 13.0.0.0.0, 4 Ajaw 3 K'ank'in, Lord of the Night G9, the famous end of the thirteenth bak'tun. The creation date returns 4 Ajaw 8 Kumk'u. January 1, 2000 returns 11 Ik' 10 K'ank'in, and a date 18,980 days later (one Calendar Round) returns the same Tzolk'in and Haab' pair, as it must.

The Aztec equivalent

The Aztec tonalpohualli uses the same structure, and its twenty day signs correspond one-to-one with the Maya ones: Imix with Cipactli (Crocodile), Ik' with Ehecatl (Wind), and so on to Ajaw with Xochitl (Flower). Whether the two counts were in step on the same day was once debated. Alfonso Caso's widely accepted reconstruction places the fall of Tenochtitlan, on August 13, 1521 in the Julian calendar, on the day 1 Coatl (1 Serpent) in the year 3 Calli (3 House). Running that date through the Maya engine gives 1 Chikchan, and Chikchan is the Serpent day. The two calendars line up exactly, so the calculator shows the Aztec day as the same number with the matching Nahuatl sign.

Aztec years were named after the day that carried them, cycling through Tochtli (Rabbit), Acatl (Reed), Tecpatl (Flint) and Calli (House) with numbers 1 to 13, for a 52-year cycle. Scholars still disagree on exactly when in the Western year each Aztec year began, so the year name here is approximate and simply counts from 1521 = 3 Calli by Western year. It reproduces 1507 as 2 Acatl, the year of the last New Fire ceremony before the Spanish conquest.

The twenty day signs

Associations are a simplified blend of colonial-era sources and modern daykeeping practice; meanings vary between communities.

Worked example: December 21, 2012

Enter 2012-12-21. The Julian Day Number is 2,456,283. Subtract 584,283 and you get 1,872,000 days since creation, which is exactly 13 × 144,000, so the Long Count reads 13.0.0.0.0. Dividing 1,872,000 + 3 by 13 leaves a remainder of 3, so the day number is 4. Adding 19 and dividing by 20 leaves 19, the twentieth sign, Ajaw. The Haab' position is (1,872,000 + 348) mod 365 = 263, which is day 3 of the fourteenth month, K'ank'in. Put together: 4 Ajaw 3 K'ank'in. In the Aztec count that day is 4 Xochitl, 4 Flower.

Despite the headlines at the time, nothing in the Maya inscriptions predicted the end of the world in 2012. The Long Count simply rolled over to a new bak'tun, much as a car's odometer rolls from 99,999 to 100,000. A monument at Palenque even refers to a date thousands of years later, in AD 4772.

A little history

The 260-day count is one of the oldest features of Mesoamerican civilization; the earliest known examples date back to at least the first millennium BC in Oaxaca and the Maya lowlands. Nobody knows for certain why 260 days was chosen. Proposed explanations include the approximate length of human pregnancy, the interval between the two zenith passages of the Sun at about 15 degrees north latitude, and the simple product of two sacred numbers, 13 and 20. It was used to schedule ceremonies, name people and guide decisions.

The Long Count, by contrast, was a linear count of days for historical records, carved on stelae to date the reigns of kings. It fell out of use after the Classic period, but the 260-day count did not. Daykeepers (ajq'ij) in highland Guatemala still keep it today, unbroken, and their count matches the GMT correlation. That living tradition is one of the strongest pieces of evidence for the correlation this calculator uses.

Using your day sign for reflection

In K'iche' tradition a person's birth day sign is thought to shape their character and calling. You do not need to share that belief to find the exercise interesting. Read the associations for your sign and treat them as questions: if your sign is Eb, the road, what path are you on and who travels with you? If it is Kawak, the storm, what needs clearing out so something can grow? The number has a role too: low numbers are often read as gentle and high numbers as intense.

The 260-day cycle also makes a natural planning rhythm. Roughly nine months long, it fits neatly over a school year, a pregnancy or a big project. Some people mark their "day sign birthday" every 260 days as a check-in point. The calculator shows your kin number (1 to 260); add 260 days to your birth date and you are back where you started.

Please approach these traditions with respect. The day signs are part of a living spiritual practice for Maya communities today, not just a historical curiosity.

Frequently asked questions

Sources and further reading

• Wikipedia: "Tzolk'in", "Haab'", "Mesoamerican Long Count calendar", "Tonalpohualli", "Maya calendar".
• Caso, A. Los calendarios prehispánicos, UNAM, 1967 (Aztec–Christian correlation).
• Kennett, D. J. et al., "Correlating the Ancient Maya and Modern European Calendars with High-Precision AMS 14C Dating", Scientific Reports 3 (2013).
• Tedlock, B. Time and the Highland Maya, University of New Mexico Press, rev. ed. 1992.
• Stuart, D. The Order of Days, Harmony Books, 2011.

By Stanley King · About 8calc · Last reviewed October 2026

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