The proportions
The arithmetic of the Mexica calendar
What it covers
Why 260 and 365 meet again only after 52 years, and the other ratios the calendar rests on, worked out in full.
The full entry is in Spanish, and here is why
What you have read above is this project's own summary of the proportions. The full entry — the part that rests on the sixteenth-century sources — has not been translated, and that is a decision rather than an omission.
We chose not to touch the primary text. Those sections quote Sahagún, Durán and the codices in their own words, often in sixteenth-century Castilian. A quotation carried across stops being a quotation: it loses the register, the ambiguity and the exact wording someone might want to check against a facsimile.
In Spanish the entry carries:
- Qué es un encuentro
- El número que no se puede evitar
- Una vejez
- La Luna no embona
Read the full entry in the original Spanish → Nahuatl names and terms are identical in both versions.
How to cite this page
Alma Mexica, «The proportions», The documents. Revised 2026-09-17. https://almamexica.org/en/document/cuentas-encuentro/