What this calculator does
The Maya tracked time with three interlocking calendars rather than one. The Long Count is a running day count from a fixed mythical starting point, written as five numbers such as 13.0.0.0.0. The Tzolkin is a 260-day sacred cycle combining a number from 1 to 13 with one of 20 named days. The Haab is a 365-day civil calendar of eighteen 20-day months plus a short 5-day period. This converter turns any Gregorian date into all three.
The link between our calendar and the Maya one is not something that can simply be read off an inscription; it relies on a correlation constant that scholars established by cross-referencing Maya dates with known historical and astronomical events. This calculator uses 584,283, the Goodman-Martinez-Thompson (GMT) correlation, which is the most widely used value in both academic and popular sources, though it is worth knowing that a small number of alternative correlation constants exist and are preferred by some researchers, which would shift every date by a few days.
The formula
The Gregorian date is first converted to a Julian Day Number, a continuous day count used by astronomers and calendar specialists. Subtracting the GMT correlation constant, 584,283, from that Julian Day Number gives the total number of days since the Long Count epoch. That day count is then broken into the five Long Count place values (baktun, katun, tun, winal and kin) and used to work out the matching position in both the 260-day Tzolkin cycle and the 365-day Haab cycle.
| Term | Meaning |
|---|---|
| Long Count | A continuous day count from the mythical creation date, written as baktun.katun.tun.winal.kin, the five place values of the Long Count system. |
| Tzolkin | A 260-day cycle combining a number from 1 to 13 with one of 20 named days, used for ritual and divinatory purposes. |
| Haab | A 365-day civil calendar of 18 months of 20 days each, plus a 5-day period called Wayeb, at the end of the year. |
| GMT correlation | The Goodman-Martinez-Thompson constant, 584,283, that fixes how the Long Count aligns with the Julian Day Number and therefore with our own calendar. |
The inputs explained
| Field | What to enter |
|---|---|
| Gregorian date | Any Gregorian calendar date to convert into its Long Count, Tzolkin and Haab equivalents. |
When to use it
Looking up a specific historical or personal date
A birthday, an anniversary or a historical event converted into the Long Count, Tzolkin and Haab gives the same date as it would have been recorded in the Maya calendar system.
Checking a famous Long Count date
Dates like 13.0.0.0.0, the end of the 13th baktun on 21 December 2012, can be checked directly against this converter using the GMT correlation that made that date well known.
Studying how the three Maya calendars interact
Because the Tzolkin repeats every 260 days and the Haab every 365 days, the combination of the two only repeats once every 52 years (the Calendar Round); converting a run of dates shows that cycle in action.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What Long Count, Tzolkin and Haab dates fall on the start of each month this year?
A run of dates through the year, each converted to its Long Count, Tzolkin and Haab equivalents.
| Gregorian date | Long Count | Tzolkin date | Haab date |
|---|---|---|---|
| 2026-01-01 | 13.0.13.3.19 | 5 Kawak | 17 K'ank'in |
| 2026-03-01 | 13.0.13.6.18 | 12 Etz'nab | 16 K'ayab |
| 2026-05-01 | 13.0.13.9.19 | 8 Kawak | 12 Wo' |
| 2026-07-01 | 13.0.13.13.0 | 4 Ajaw | 13 Sek |
| 2026-09-01 | 13.0.13.16.2 | 1 Ik' | 15 Mol |
| 2026-11-01 | 13.0.14.1.3 | 10 Ak'bal | 16 Sak |
Questions
Why 584,283 specifically?
It is the Goodman-Martinez-Thompson correlation constant, derived by matching Long Count dates recorded on Maya monuments against verifiable historical and astronomical events. It is the correlation most widely used in both scholarly and general references, though it is a researched best-fit value, not something inscribed by the Maya themselves.
Are there other correlation constants?
Yes. A handful of alternative correlations have been proposed over the years, each shifting the calculated date by a small number of days. The GMT correlation used here (584,283) remains the standard default in most modern sources.
What does a Long Count like 13.0.0.0.0 mean?
Reading right to left, it is 0 kin (days), 0 winal (20-day periods), 0 tun (360-day periods), 0 katun (7,200-day periods) and 13 baktun (144,000-day periods) since the Long Count epoch, a date that corresponds to 21 December 2012 in the Gregorian calendar under the GMT correlation.
Why do the Tzolkin and Haab both matter if the Long Count already gives a unique date?
The Long Count was mainly used on monumental inscriptions. In everyday life the combined Tzolkin and Haab date, known as the Calendar Round, was the more commonly cited reference, similar to how a modern date might be given with the day of the week attached.
For everyday date arithmetic on the Gregorian calendar, see the date calculator. For the plain day count between two calendar dates, use the days calculator.