How to use it
- Choose Convert: From a date or From a Long Count.
- Enter the Date, or type the Long Count in the form 13.0.0.0.0.
- Read Long Count, Tzolk'in (260-day count) and Haab (365-day count). The Julian Day Number is the figure to compare with another converter.
The three counts
The Maya used three counts together. The Long Count counts the days from a fixed zero day in units of 20: a kin is one day, a uinal 20 days, a tun 18 uinals (360 days), a katun 20 tuns (7,200 days) and a baktun 20 katuns (144,000 days). The Tzolk'in is a 260-day count of a number from 1 to 13 with one of 20 day names. The Haab is a 365-day year of 18 months of 20 days, followed by Uayeb, five days.
Each day has one reading in each count, so the three readings of one day always go together.
Tzolk'in: number = ((days + 3) mod 13) + 1; name = Imix, Ik, Akbal ... Ahau, counted from (days + 19) mod 20
Haab: position = (days + 348) mod 365; month = position ÷ 20 (whole part); day = position mod 20The correlation with our calendar
The Long Count does not say which day of our calendar it is. The page uses the GMT correlation: the zero day, 4 Ahau 8 Cumku, has Julian Day Number 584283, which is 11 August 3114 BC in the proleptic Gregorian calendar. Martin and Skidmore's 2012 article gives that constant and the zero day, and its example for 15 July 1553 in the Julian calendar reads 12 K'an 2 Pop in the Classic count. This page gives the same reading for 25 July 1553 in the Gregorian calendar. Some authors write the zero day as 13.0.0.0.0, the start of the current cycle; this page counts it as 0.0.0.0.0, so 13.0.0.0.0 is 21 December 2012.
Other constants have been proposed. The Goodman, Martinez and Thompson (GMT) correlation is a family of constants from 584280 to 584285, and the 2012 article explores 584286. Of the two most widely accepted values, the page uses 584283, the one Thompson arrived at in 1950.
What this page does not cover
- Dates before 15 October 1582 or after 31 December 2100. Earlier dates were written in the Julian calendar and need a separate conversion.
- The colonial numbering of the Haab, which starts a month at 1 instead of 0. This page follows the Classic numbering, in which the first day of the year is 0 Pop.
- Historical events, the year bearers of a given year, and the dates of Maya rulers. The page converts the calendar only.
Worked example: 13.0.0.0.0 (21 December 2012)
The Long Count 13.0.0.0.0 is the end of the thirteenth baktun. With the GMT correlation it falls on 21 December 2012 in the Gregorian calendar. The page gives these values for that date:
| Output | Value |
|---|---|
| Long Count | 13.0.0.0.0 |
| Tzolk'in (260-day count) | 4 Ahau |
| Haab (365-day count) | 3 Kankin |
| Days since the zero day | 1,872,000 |
| Julian Day Number | 2,456,283 |
Frequently asked questions
What is the Long Count?
The Long Count writes the days since a zero day as five numbers: baktuns of 144,000 days, katuns of 7,200 days, tuns of 360 days, uinals of 20 days and kins of one day. The date 13.0.0.0.0 is the end of the thirteenth baktun.
Why do the Tzolk'in and Haab names come back again?
The Tzolk'in has 260 days and the Haab has 365, so the two counts line up again only after 18,980 days, which is 52 Haab years. This period is called the Calendar Round.
Is the GMT correlation certain?
No. It is the most widely used link between the Maya count and our calendar, but scholars still debate the constant. Martin and Skidmore's 2012 article explores 584286, and other constants from 584280 to 584285 have been proposed.
Why does a Haab day look one number higher in some books?
The Classic inscriptions number the days of a month from 0, so this page writes 0 Pop for the first day of the year. The colonial Yucatec sources number from 1, so the same day appears one number higher there.
Can the page convert dates before 1582?
No. The page converts from 15 October 1582, the first day of the Gregorian calendar, to 31 December 2100. Earlier dates were written in the Julian calendar, so they need their own conversion first.
Is the date I enter sent anywhere?
No. The conversion runs in your browser, and nothing you enter is stored or sent to a server.
Sources
- Martin, Simon and Joel Skidmore, Exploring the 584286 Correlation, PARI Journal 13(2), 2012, pp. 3-16
- University of Delaware, The Maya Calendar: Long Count, Tzolk'in and Haab names
Figures and text last checked on Wednesday, November 11, 2026.