Calendar Maya Calculator
Mayan Calendar Converter works out Long Count and Tzolk’in date from Gregorian date and Correlation constant. The default figures on this page give long Count of 13.0.0.0.0; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
5 steps
- 2012-12-21 has Julian Day Number 2456283.
- Days since the Long Count zero date: 2456283 - 584283 = 1872000.
- Long Count: 1872000 = 13 x 144000 + 0 x 7200 + 0 x 360 + 0 x 20 + 0 = 13.0.0.0.0.
- Tzolk’in: number = ((1872000 + 3) mod 13) + 1 = 4; day name index = (1872000 + 19) mod 20 = 19 = Ajaw.
- Haab’: (1872000 + 348) mod 365 = 263, which is day 3 of K’ank’in.
Its 3 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
What the Mayan Calendar Converter calculates
Converts a Gregorian date into the Maya Long Count, the 260-day Tzolk’in round (a number 1-13 with one of 20 day names) and the 365-day Haab’ year, using the Goodman-Martinez-Thompson correlation constant 584283 that places 13.0.0.0.0 on 21 December 2012. Haab’ days are numbered from 0, the seating of the month, as in the Smithsonian converter.
How to use this Mayan Calendar Converter
Enter Gregorian date and Correlation constant. Long Count updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Long Count, Tzolk’in date and Haab’ date.
The method follows Smithsonian National Museum of the American Indian, "The Calendar System", Living Maya Time, Smithsonian National Museum of the American Indian, Maya Calendar Converter and J. Eric S. Thompson, Maya Hieroglyphic Writing: An Introduction (Goodman-Martinez-Thompson correlation, constant 584283).
The end of the 13th b’ak’tun, 21 December 2012 example
With Gregorian date: 2012-12-21, Correlation constant: gmt_584283, the calculator returns Long Count: 13.0.0.0.0, Tzolk’in date: 4 Ajaw, Haab’ date: 3 K’ank’in. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Long Count, Tzolk’in date and Haab’ date. The inputs you can vary are Gregorian date and Correlation constant.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
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Frequently asked questions
What information do I need for the Mayan Calendar Converter?
You need Gregorian date and Correlation constant. The page opens with default figures that give long Count of 13.0.0.0.0, so you can see the scale before entering your own.
What does this Mayan Calendar Converter show?
It shows Long Count, Tzolk’in date, Haab’ date, Calendar Round, Julian Day Number, Days since the Long Count zero date, B’ak’tun and K’atun, with the working and any warnings for your entries.
Can I check how the Mayan Calendar Converter result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.