The 260-Day Count

Twenty day-signs turn against thirteen numbers. Neither cycle waits for the other, so a pairing does not repeat until 260 days have passed. That count is the Tzolk'in, and it has been kept without a break for well over two thousand years.

Picture two gears. The number wheel steps 1 through 13 and starts again. The sign wheel steps through its twenty signs and starts again. Day one carries number 1 with the first sign; day fourteen brings number 1 back, but the sign has moved on. Only after 260 days do both wheels land where they began.

Three explanations circulate for the 260, and none is settled. One is human gestation, which runs close to that length. Another is the sun: at about 15 degrees north — the latitude of Copan and Izapa — the gap between the two days a year it stands directly overhead comes out near 260. A third is simpler, that 13 and 20 each mattered on their own and 260 is their product.

The Tzolk'in does not track the seasons, and it was never meant to — the Maya kept a separate 365-day count, the Haab', for that. The two ran side by side: one for where you are in the year, one for what kind of day it is. Daykeepers in the Guatemalan highlands still count the Tzolk'in, day by day.

What comes out is a name, not a date: 8 Imix', 9 Ik', 10 Ak'bal. A number for how strongly, a sign for what kind. That pairing has been counted every single day for more than two thousand years.