Maya Long Count
Convert a Gregorian date to the Maya Long Count (baktun.katun.tun.winal.kin).
Overview
The Maya Long Count converter turns any Gregorian date into the five-component Long Count notation used by the ancient Maya: baktun, katun, tun, winal, and kin. Enter a Gregorian date and you get a string like 13.0.13.10.18 along with the day-of-creation count and the associated Tzolkin and Haab almanac dates.
Useful for archaeoastronomers and Mesoamerican scholars, fiction writers building Maya-themed settings, teachers covering the 2012 phenomenon, museum exhibit curators, and anyone curious about the calendar that famously rolled over on 2012-12-21 (13.0.0.0.0).
How it works
The Long Count is a continuous tally of days since the Maya creation date, which the GMT (Goodman-Martínez-Thompson) correlation places at 11 August 3114 BC in the proleptic Gregorian calendar (JDN 584283). Days are grouped into units of 20 (kin → winal), then 18 (winal → tun, making a tun exactly 360 days), then 20 (tun → katun), then 20 again (katun → baktun). Most modern Long Count dates therefore start 13.x.x.x.x.
The Tzolkin almanac cycles every 260 days (13 numbers paired with 20 named days), and the Haab civil year runs 365 days (18 months of 20 days plus a 5-day Wayeb period). Both run alongside the Long Count and are reported in the converter output.
Examples
2012-12-21 → 13.0.0.0.0 — 4 Ajaw, 3 K'ank'in (end of the 13th baktun)
2026-05-18 → 13.0.13.10.18
1969-07-20 → 12.17.15.16.4 (Apollo 11 lunar landing)
−3114-08-11 → 0.0.0.0.0 (creation date, day zero)
FAQ
Did the Maya calendar predict the end of the world in 2012?
No — December 21, 2012 was simply the end of the 13th baktun, the rollover of one large cycle. Maya inscriptions reference dates well beyond it, including one carved at Palenque that lies 4 octillion years in the future.
What is the GMT correlation?
The Goodman-Martínez-Thompson correlation maps Maya day numbers to Julian Day Numbers. JDN 584283 is the most widely accepted correlation constant and is what this tool uses.
Why is a tun 360 days and not 365?
The Long Count is a pure mathematical day count, not a solar calendar. Aligning to 360 keeps the unit system consistent (20 × 18 × 20 × 20 day-units stack cleanly). Solar drift is handled separately by the Haab.
What are the Tzolkin and Haab?
Two independent almanac cycles that run alongside the Long Count. The Tzolkin is a 260-day ritual cycle; the Haab is a 365-day approximate solar year. Together they form the 52-year Calendar Round.
How far back does the Long Count go?
Day zero is the creation date, 11 August 3114 BC. Dates before that are written with negative components and are rare in inscriptions.