This article is from the Calendars FAQ, by Claus Tondering email@example.com with numerous contributions by
8.3. What is the Haab? (Maya Calendar)
The Haab was the civil calendar of the Mayas. It consisted of 18
"months" of 20 days each, followed by 5 extra days, known as
"Uayeb". This gives a year length of 365 days.
The names of the month were:
1. Pop 7. Yaxkin 13. Mac
2. Uo 8. Mol 14. Kankin
3. Zip 9. Chen 15. Muan
4. Zotz 10. Yax 16. Pax
5. Tzec 11. Zac 17. Kayab
6. Xul 12. Ceh 18. Cumku
In contrast to the Tzolkin dates, the Haab month names changed every
20 days instead of daily; so the day after 4 Zotz would be 5 Zotz,
followed by 6 Zotz ... up to 19 Zotz, which is followed by 0 Tzec.
The days of the month were numbered from 0 to 19. This use of a 0th
day of the month in a civil calendar is unique to the Maya system; it
is believed that the Mayas discovered the number zero, and the uses to
which it could be put, centuries before it was discovered in Europe or
The Uayeb days acquired a very derogatory reputation for bad luck;
known as "days without names" or "days without souls," and were
observed as days of prayer and mourning. Fires were extinguished and
the population refrained from eating hot food. Anyone born on those
days was "doomed to a miserable life."
The years of the Haab calendar are not counted.
The length of the Tzolkin year was 260 days and the length of the Haab
year was 365 days. The smallest number that can be divided evenly by
260 and 365 is 18,980, or 365*52; this was known as the Calendar
Round. If a day is, for example, "4 Ahau 8 Cumku," the next day
falling on "4 Ahau 8 Cumku" would be 18,980 days or about 52 years
later. Among the Aztec, the end of a Calendar Round was a time of
public panic as it was thought the world might be coming to an
end. When the Pleiades crossed the horizon on 4 Ahau 8 Cumku, they
knew the world had been granted another 52-year extension.