Mayan calendar

The Maya had three calendars:

a sacred calendar, called tzolkin
a civil calendar, called haab
long count, which was used for inscriptions.

Tzolkin or sacred calendar

drawing of the glyphs for the 20 'months' in the Mayan sacred calendar

The sacred year consisted of 20 “months” of 13 days each. Each of the 13 days and each of the 20 “months” has a name. Both the “months” and days cycle continuously; each new day is in a new “month.” It is as if, in the Gregorian calendar, 6 January was followed by 7 February followed by 8 March. Since 13 and 20 have no common factor, there are 260 unique names for days, and the sacred year is 260 days long.

Since a date in the sacred calendar has no year component, it is not possible to convert a date like “5 Ix” to (for example) the Gregorian calendar. However, it is possible to find what the Tzolkin name for a date in the Gregorian calendar would be:

Haab or secular calendar

drawing of the glyphs for the 18 uinals in the Mayan secular calendar

In the secular calendar, a year consisted of 18 uinals, which is a period of 20 days. 18 × 20 = 360 days, with five days left over, an annual unlucky period called Uayeb. The first day of the uinal was 0, and the last was 19, followed by day 0 of the next uinal.

Like the sacred calendar, it is not possible to convert a date like “5 Kankin” to, for example, the Gregorian calendar, since it has no year component.

It was usual to give both the sacred and civil name for a day. A day thus described will not recur for 52 civil years, or 73 sacred years.

The long count

The long count was used for inscriptions. It is a count of the number of days since the beginning of the current period.

							alantun
						kinchiltun		20
					calabtun		20	400
				pictun		20	400	8,000
			baktun		20	400	8,000	160,000
		katun		20	400	8,000	160,000	3,200,000
	tun		20	400	8,000	160,000	3,200,000	64,000,000
uinal		18	360	7,200	144,000	2,880,000	57,600,000	1,152,000,000
kin (sun)	20	360	7,200	144,000	2,880,000	57,600,000	1,152,000,000	23,040,000,000
1 day	30 days	360 days	about 19.7 Greg. years	about 395 Greg. years	about 7,885 Gregorian years	about 157,703 Gregorian years	about 3,154,069 Gregorian years	about 63,081,377 Gregorian years

Today historians write dates in the long count in the following form (the date given is the beginning of the present era): 13. 0. 0. 0. 0. 4 Ahau, that is baktun. katun. tun. uinal. kin., followed by the name of the day in the sacred calendar.

Using astronomical events recorded both by Mayan and European astronomers, and historical events whose dates were recorded both by Spaniards and civilizations using the Mayan calendar, scholars have sought to correlate the Mayan and Gregorian calendars. According to the most widely accepted correlation (the “Goodman-Martinez-Thompson Correlation”) the current Mayan epoch began on Wednesday 11 August 3113 bce (Gregorian) which is Julian date 584,282.5.