The 365-day solar calendar
Eighteen named months of twenty days, then Wayeb' — five "nameless" days that close the year. It is called a vague year because it has no leap-day correction: 365 whole days against a tropical year of about 365.2422, so the Haab' slips roughly one day every four years against the seasons and completes a full lap in about 1,507 years.
Eighteen months and Wayeb'
The current month is outlined. Wayeb' is marked in red — a liminal, inauspicious span when, per Landa's colonial account, people minimized activity and performed year-renewal rites.
"Seating," not day zero
Maya scribes did not write "0 Pop." The first day of a month is its seating — chum — as though the month takes its seat before its count begins. So a date runs: seating of Pop, then 1 Pop, 2 Pop … up to 19 Pop, then the seating of the next month. This reference writes the seating day as "Seating of <month>."
The same logic governs the Long Count's period endings, which is why a k'atun ends on a day like 13.0.0.0.0 — a completion, a seating of the next unit.
The four days that can carry a year
Because 365 mod 20 = 5, only four of the twenty day signs can ever coincide with a fixed Haab' station — and the set depends on which station is used as the New Year anchor. Two systems are historically attested.
| System | Anchor station | Year-bearer set | Attested |
|---|---|---|---|
| Classic (Tikal) | seating of Pop | Ik' · Manik' · Eb' · Kaban | Classic monuments at Tikal and much of the central lowlands |
| Colonial (Yucatec) | "1 Pop" (= Classic 2 Pop under GMT 584283) | K'an · Muluk · Ix · Kawak | Landa; the Books of Chilam Balam; post-conquest Yucatán |
Where 1 Pop lands across the centuries
With no leap correction, the Haab' New Year moves steadily earlier in the Gregorian year. Same Haab' date, different season, century by century.