What is the Maya Tzolkʼin?
A calendar you can check against carved stone — and what we refuse to invent.
The idea, in plain words
The Maya kept several calendars at once and read a date as all of them together. The one people usually mean is the Tzolkʼin: a 260-day sacred count made of 13 numbers turning against 20 named days. Number and name step forward side by side — 1 Imix, 2 Ikʼ, 3 Akʼbʼal — and after 260 days the pair you started with comes back around.
The day you were born has a name in that count. Maya tradition calls it your nawal. It is not a verdict on your life; it is the character of the day you arrived on, and the number beside it is how strongly that day was running.
How Bokki calculates it
Everything comes from one number: how many days have passed since the Maya era base. Bokki turns your date into a Julian Day Number, subtracts 584283, and the whole date falls out of that single count by plain arithmetic.
That constant is the whole game. 584283 is the GMT correlation — Goodman, Martínez and Thompson — the day in our calendar that carries Long Count 0.0.0.0.0, which the Maya wrote 4 Ajaw 8 Kumkʼu. It is the standard, and it is still a choice: the rival constant 584285 moves every result by two days. A Maya date you cannot trace back to a constant is a date you cannot check, so we pin 584283 and say so on the page.
From that elapsed count: the tone is ((3 + elapsed) mod 13) + 1 and the day-sign is (19 + elapsed) mod 20. The Haabʼ — the 365-day year of eighteen 20-day months plus the five nameless days of Wayebʼ — is (348 + elapsed) mod 365. The Long Count is the same number written in base 20, 18, 20, 20: bʼakʼtun, kʼatun, tun, winal, kʼin. The Lord of the Night is ((elapsed + 8) mod 9) + 1.
Because it is arithmetic and not opinion, it can be checked — so we check it. Our tests pin seven carved dates, each a Long Count written beside its Calendar Round, with the Gregorian day our constant gives them — among them 13.0.0.0.0 = 4 Ajaw 3 Kʼankʼin = 21 December 2012, and Pakal's accession at Palenque, 9.9.2.4.8 = 5 Lamat 1 Mol = 27 July 615. If a change ever broke the arithmetic or moved the constant, those tests would go red before anybody saw a wrong date.
One more thing falls out for free. The Tzolkʼin and the Haabʼ return to the same pairing every 18,980 days — 52 haabʼ, 73 tzolkʼin — so Bokki can also name the exact Gregorian date on which your own Calendar Round comes round again.
What we do not calculate
We do not use the Dreamspell. José Argüelles' 1987 system also has 13 tones and 20 signs, but it runs a different day count, so for most birthdays it gives a different answer from the traditional one. It is a modern creation, not the long count the Maya kept. If a site hands you a colour, a Kin number and a galactic signature, that is Dreamspell, and it is not what Bokki computes.
We do not give the Lords of the Night meanings. There were nine and they cycle with the days, but their names are lost. Epigraphers write G1 through G9 and nothing more is known. Bokki gives you the number and stops there.
We do not read the Haabʼ month as a personality. The Haabʼ is a date — a position in the solar year — and the tradition does not treat it the way it treats the nawal. Several month names have disputed etymology. Inventing a meaning for one would be exactly the failure this project exists to refuse.
And we are not daykeepers. The living authority on this count is the modern Maya ajqʼij — a trained person inside a community, in Guatemala and Mexico, where the 260-day count has never stopped being kept. Bokki computes the date. Reading a life from it belongs to them.
Why every day has two names
In Bokki you will see two names for the same sign: Imix and Imox, Ajaw and Ajpu. The first is Yucatec, the spelling most books use; the second is Kʼicheʼ, the language of many daykeepers today. Maya is not one language but a family of around thirty living ones, and the count is still kept in several of them. Printing one name only would quietly pick a winner, so we print both and label which is which.
Closing note — one subtracted number, and what holds it in place
In short: your whole Maya date falls out of one subtraction — Julian Day Number minus 584283, the GMT correlation — and every other number on the page (tone, day-sign, Haabʼ position, Lord of the Night, Long Count) is plain arithmetic on that one elapsed count. Be exact about what holds the constant in place. The seven carved dates our tests pin, from 13.0.0.0.0 to Pakal's accession at Palenque, 9.9.2.4.8, prove the arithmetic — each carved date pairs a Long Count with a Calendar Round, and we reproduce all seven — but they cannot choose the constant: 584285 reproduces every one of them too, only landing each on a Gregorian day two later. What chooses 584283 lies outside the stones. Radiocarbon on a carved Tikal lintel (Kennett and colleagues, 2013) rules out correlations centuries away, and the 260-day count highland Kʼicheʼ daykeepers still keep put 8 Bʼatzʼ on 18 January and 5 October 2025 — the days 584283 gives, and two days from what 584285 would give.
The same arithmetic gives you something for free: the Tzolkʼin and the Haabʼ return to the same pairing every 18,980 days — 52 Haabʼ cycles, 73 Tzolkʼin cycles — so Bokki can also name the date your own Calendar Round comes around again. What none of that arithmetic tries to do is speak for a living tradition: the Lords of the Night keep their numbers (G1 through G9) because their names are genuinely lost, and reading a life from a nawal is left to the ajqʼij who still keep this count in Guatemala and Mexico today — which is also why every day-sign on this page carries two names, Yucatec and Kʼicheʼ, instead of one language quietly standing in for all of them.