Aztec (Mexica)
Xiuhpōhualli & Tōnalpōhualli · the Caso correlation
The Mexica kept two interlocking counts, as the Maya did: the 365-day Xiuhpōhualli of eighteen twenty-day veintenas plus five unlucky nemontemi, and the 260-day Tōnalpōhualli of twenty day-signs against thirteen numbers. Dates follow the Caso correlation, anchored to the fall of Tenochtitlan — 13 August 1521 by the Julian calendar then in use, which is 23 August in the Gregorian terms this site reckons in — recorded as 1-Cōātl. The two counts ran in step with the Maya, so the day-sign here matches the Tzolkʼin’s.
In UTC at 02:02 on October 27, 2026, this calendar read 5 Tecpatl. The reading above is live, in your own time zone.
At a glance
- Type
- Cyclical — a 365-day year turning against a 260-day sacred round
- Origin
- The Aztec (Mexica) civilization of Mesoamerica
- Year
- The 365-day Xiuhpōhualli
- Months
- 18 veintenas of 20 days, plus 5 (the nemontemi)
- Week
- No week; a 260-day sacred round (the Tōnalpōhualli)
- Leap rule
- None
- Counts from
- No running count; years turn in a 52-year round
- Where it’s used
- Historical (Caso correlation)
- How it’s worked out here
- The Caso correlation, anchored to the fall of Tenochtitlan on the day 1-Cōātl
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