Calendar Correlation

Sven Gronemeyer

This is a Java-Script based conversion programme. You can only enter Long Count information that can be converted into Calendar Round date, Gregorian Date and Julian Day Number. There is only a one-to-one relation in computing the result. Therefore, vacant digits or wildcards are not allowed.

Note: the converter only allows Long Count dates after the creation date to be entered. The calculation of mythological dates is not possible. Erroneous values will be corrected to the minimal or maximal possibility for each coefficient.

The preset correlation constant is the standard GMT with the value “584285”. But any other number between 250000 and 850000 can be entered. Lesser or higher values will be corrected to the minimal or maximal possibility.

Long Count:







Calendar Round:



Gregorian Date:




Julian Day Number:

We also include two correlation programmes for download that are rather old, from before the mid-nineties, and need to be run under DOS-Mode. We still consider them to be quite useful as none of the newer programmes that run under Windows offers the same variety of modes.
The software is provided in a zipped archive and needs no further installation.

Windows Vista and Windows 7 users: In order to get the software running, you need to install a DOS emulator first and run the software from there. The compability mode won’t function. DOS Box is a suitable tool. Users of Windows XP and below can run the software from the command line or via the compability mode.

Mayan Calendrics – by Marc Harris and John Harris
MayaCal – by Linda Schele

Further information about running MayaCal: This is a collection of single programmes. The individual modules are uncompiled BAS-files for Microsoft™ GW-Basic, Ver. 3.22. The compiler (file BASICA.EXE) is enclosed. First start the compiler, then load the programme with the command LOAD”MAYACAL and run it by hitting F2. A termination of MayaCal is possible hitting CTRL+BREAK, by typing SYSTEM you will quit to your OS.

If you are looking for a programme capable of running under a 64-bit architecture, you may want to download MayaDate.

Related Links

OKMA Calendar

An online calendar correlation tool with a variety of calculated cycles and visual output.