The Aztec ritual calendar, called the tonalpohualli, contained 260 days.
Its cycle was formed by combining 20 day signs with 13 numbers. Each day received one sign-number pairing, producing 13 × 20 = 260 distinct combinations before the sequence repeated. The day signs included symbols such as Crocodile, Wind, House, Jaguar, Eagle, and Flower.
The tonalpohualli was a sacred divinatory calendar rather than a simple solar year. Priests used its day signs and numbers to assess the character or omen of a day, helping guide ceremonies, naming, and other important decisions. The same 260-day structure also appears in other Mesoamerican calendrical traditions, including the Maya tzolk’in.
A frequent mistake is choosing 365, which belonged to the separate solar cycle called the xiuhpōhualli. The two cycles moved together: a 260-day ritual cycle and a 365-day seasonal cycle took about 52 solar years to return to the same combined date, forming a calendar round.