Your Aztec day sign

The day-sign and number of the day you were born in the 260-day count: 5-Coatl, 9-Ocelotl, and so on. It is not a zodiac sign — there are twenty signs, not twelve, and they follow the day rather than the month. This page computes it from a birth date, in the browser, without sending the date anywhere.

There is no Aztec zodiac in the astrological sense: no twelve houses, no planets assigned to characters, no birth chart. What the sources record is the tonalpohualli, a 260-day count that was used for divination — which is a different apparatus, built on signs, numbers, energies and directions rather than on celestial bodies.

No. The calendar is two counts of days, and it is documented in the sixteenth-century sources. «Aztec astrology» is a modern label, usually applied to material that borrows the twenty signs and adds a framework the sources do not contain.

Twenty, not twelve. The twelve comes from forcing the tonalpohualli onto the Western zodiac. They are Cipactli, Ehecatl, Calli, Cuetzpalin, Coatl, Miquiztli, Mazatl, Tochtli, Atl, Itzcuintli, Ozomatli, Malinalli, Acatl, Ocelotl, Cuauhtli, Cozcacuauhtli, Ollin, Tecpatl, Quiahuitl and Xochitl, and each pairs with thirteen numbers.

No. The signs run day by day, not in month-long stretches: 4 January is one sign and 5 January is another. Tables giving «21 March to 29 April» are mapping the tonalpohualli onto the Western zodiac, which has a different structure. And because the count is 260 days against a 365-day year, the same calendar date does not repeat its sign from one year to the next.

No. Both cultures use a 260-day count — tonalpohualli among the Mexica, tzolk'in among the Maya — and share a common Mesoamerican background, but neither the sign names nor the starting point coincide, and one is not derived from the other.

Because each uses a different correlation — an anchor fixing which Aztec day matches a given Gregorian date — and almost none of them say which. At least five are in circulation and there is no scholarly consensus on which is right. This site publishes all five with their anchor and their source, rather than returning a result without saying where it comes from.

It depends on the correlation it uses, which is why you should ask which one. The arithmetic of the tonalpohualli is not in dispute: twenty signs by thirteen numbers. What is disputed is the starting point, and the proposals differ by days. A calculator that does not declare its anchor cannot be called accurate.