Mayan Calendar Calculator - Tzolk'in, Haab, Long Count, and Lord of the Night

A Mayan calendar calculator is a one-page tool that converts a Gregorian date into the four interlocking Mayan date labels (long count, Tzolk'in sacred round, Haab solar year, and Lord of the Night), and that also reads a long count such as 13.0.0.0.0 back to a Gregorian date. It uses the Goodman-Martinez-Thompson (GMT) correlation at JDN 584,283.

• • Birthday lookup: Find what Tzolk'in, Haab, and Lord of the Night labels fall on a modern Gregorian birthday.
• • Historical archaeology: Convert a Maya inscription's long count back to a Gregorian date to compare with the European record.
• • 2012 end-of-cycle study: Confirm that 21 December 2012 corresponds to long count 13.0.0.0.0, the start of the 13th b'ak'tun.
• • Calendar math: Verify how a 260-day sacred round and a 365-day solar year interlock with the long count position.

The Maya tracked time with four parallel calendars: the 260-day Tzolk'in, the 365-day Haab, the five-position long count, and the nine-position Lord of the Night. The long count makes the system repeat only once every 5,125 years.

To read each long count position as dots, bars, and a shell glyph for zero, Mayan Numeral Calculator turns any decimal value up to 3,199,999 into the base-20 Maya glyph stack.

The calculator reads the direction selector and the active input block, converts to a Julian Day Number (JDN), subtracts 584,283 to get the elapsed days since creation, then peels off the long count plus the Tzolk'in, Haab, and Lord of the Night labels from that elapsed-days value.

• direction: gregorian-to-mayan reads the date inputs and emits the four Mayan labels; long-count-to-gregorian reads the five long count positions and emits the matching Gregorian date plus the four labels.
• gregorianYear / gregorianMonth / gregorianDay: Gregorian date inputs. Year accepts negative integers for BCE dates down to -3113.
• baktun, katun, tun, uinal, kin: Long count positions for long-count-to-gregorian. b'ak'tun accepts 0 to 19, matching the Maya vigesimal range; uinal caps at 17 and the rest at 19.

The Tzolk'in position comes from elapsed days modulo 13 for the number and modulo 20 for the day name. The Haab position comes from elapsed days modulo 365, with days 360 to 364 falling in the five-day wayeb' unlucky period. The Lord of the Night comes from elapsed days modulo 9, anchored so the creation day reads G 9.

According to World History Encyclopedia: Mesoamerican Long Count Calendar, the Long Count uses 1 b'ak'tun = 144,000 days, 1 k'atun = 7,200 days, 1 tun = 360 days, 1 uinal = 20 days, and 1 k'in = 1 day, anchored to 11 August 3114 BCE.

Four short ideas cover the pieces of the Mayan calendar system that the calculator returns. Once they are clear, the four label rows on the result panel stop being four unrelated strings and start being one date described from four angles.

These four pieces turn a single Gregorian day into four overlapping labels: the long count gives the absolute position, the Tzolk'in gives the ritual position, the Haab gives the solar position, and the Lord of the Night gives the underworld-day position.

According to World History Encyclopedia: Tzolk'in Calendar, the sacred round combines a 13-day number cycle with a 20-day name cycle (Imix through Ajaw), producing 13 x 20 = 260 unique day combinations before it repeats.

To see the same Gregorian-to-foreign-year conversion for a planetary year, Age On Other Planets Calculator takes a birthday and returns an age in Mercury, Venus, Mars, Jupiter, and Saturn years.

Pick a direction, type either a Gregorian date or a long count, and the result panel updates in real time.

1. 1 Pick the conversion direction: Choose Gregorian date -> Mayan labels or Long count -> Gregorian date plus the four labels.
2. 2 Type a Gregorian date (or use a negative year for BCE): Enter the year, month, and day. For BCE, type the year as a negative number (e.g. -3113 for 11 August 3114 BCE). February allows 29 only in leap years.
3. 3 Or type a long count: Switch to long-count-to-gregorian and enter b'ak'tun, k'atun, tun, uinal, k'in as five numbers.
4. 4 Read the long count row: The Long Count row shows the five-number position, for example 13.0.8.12.10. Each k'in is one day.
5. 5 Read the Tzolk'in, Haab, and Lord of the Night rows: Tzolk'in shows a 1-13 number plus a 20-day name. Haab shows a 1-20 day plus an 18-month name, or a wayeb' day. Lord of the Night shows G 1 through G 9 plus the deity name.
6. 6 Cross-check with the Gregorian Date row: The Gregorian Date row formats the input date (or the date implied by the long count) as dd/mm/yyyy with a BCE suffix when needed.

Example: a teacher wants to show students that 21 December 2012 was the start of the 13th b'ak'tun, not an apocalypse. They pick the gregorian-to-mayan direction, type year 2012, month 12, day 21, and read long count 13.0.0.0.0.

For plain days, weeks, or months between two modern Gregorian dates, Date Difference Calculator returns the same kind of day count from any start and end date.

The Mayan calendar looks complex because it uses four labels instead of one, but each label is deterministic and the math behind it is short.

• • Four labels in one place: The long count, Tzolk'in, Haab, and Lord of the Night all update from the same elapsed-days value.
• • Two-way conversion: Switch the direction to read a long count from an inscription back to a Gregorian date, then verify the result by switching back.
• • BCE dates back to the creation day: Type a negative year to enter a date as far back as 11 August 3114 BCE.
• • Live update on every change: Change any input and the result panel updates instantly. No Calculate button to forget.
• • Validation for impossible dates: The calculator rejects 30 February, 31 April, 29 February in non-leap years, and dates before the creation day.
• • Same source as scholarly references: The 584,283 creation-day offset matches the GMT correlation, the most widely cited correlation in Mayan studies.

The biggest practical win is that the four labels cannot drift apart: they all come from the same elapsed-days value, and a single change to any input rewrites all four rows at once.

For the same date math on a modern problem, like total years, months, and days of employment across multiple jobs, Work Experience Calculator sums date ranges and subtracts overlaps or gaps from work histories.

The four Mayan labels are deterministic, but the inputs that drive them have a few important limits.

• • The calculator uses the GMT correlation. An inscription written using a different Mayan correlation will be off by a small fixed number of days.
• • The Haab and Tzolk'in labels assume the Maya convention that the day starts at sunrise.

Within those limits the calculator matches the published GMT correlation at JDN 584,283, the same constant used in standard Long Count references.

According to World History Encyclopedia: Haab' Calendar, the Haab' is a 365-day solar year made up of 18 named months of 20 days each (Pop through Kumk'u) plus a five-day wayeb' period.

To see how a numeric day offset can anchor a calendar, Unix Time Calculator uses a Unix epoch offset the same way this calculator uses the GMT JDN 584,283 anchor.