The Maya used three calendars -- two counting cycles, the tzolk’in and the haab that counted the days in the year, and a third that tallied years, called the Long Count.

The Tzolk’in and the Haab

The tzolk’in is a cycle of 260 days, with a sequence of 20 day names divided into 13-day “weeks.”  There are several theories regarding the origin of the 260-day cycle.  260 days is the agricultural growth cycle in Mesoamerica.  It is also the gestation period of the human female and the interval of the appearance of Venus.

The haab is a 365-day cycle similar to our solar year.  It consists of 18 months of 20 days each, with a 5-day “short month” at the end, to total the 365 days of the solar cycle.

The Calendar Round

The Maya linked together the tzolk’in and the haab to create a larger cycle of 52 years, a cycle we call the Calendar Round.  Only after completion of 52 years would the same combinations of tzolk’in and haab repeat.  The Calendar Round was used to plan planting, hunting, leadership changes, and war.  Because it was used to plan religious and ritual events, it is also called the Divinatory Calendar.

Long Count

In order to keep track of hundreds of years of history as well as to record celestial observations, the Maya developed a third calendar system, the one we call the Long Count. Similar to our year count, the Maya Long Count moves forward one place per year from a specific base date. The Maya base date is August 12, 3114 BC. Scholars have not yet determined the significance of this date.

In the representation below, the smallest, interior gear bears symbols of the 13 day numbers that mesh with the 20 named days on the exterior gear.  Together, they represent the tzolk’in. The largest gear, shown in part along the bottom of the drawing, represents the haab. When combined, the two calendar systems produce the Calendar Round.