Educator How-To: Calculating your birthday in Maya Long Count

Adapted from “Cracking the Maya Code,” a NOVA activity.

We’re familiar with a method of tracking time that uses days, months, years, decades, and centuries. This method of timekeeping is based upon the Gregorian Calendar System. The Maya, however, measured time in kins, uinals, tuns, katuns and baktuns using a system called the Long Count.  If you add the numbers in a Maya Long Count date, the sum is the number of days from the beginning of the Maya Fourth Creation:  August 13, 3114 B.C.

Educator How-To: Calculate your birthday in Maya Long CountMaya Long Count dates are written as a series of numbers separated by periods. For example,  12 . 18 . 14 . 11. 16 (December 31, 1987) is the date you will use as a starting point for your calculations. The same date is shown below in its separate component parts above its representative glyph.

Educator How-To: Calculate your birthday in Maya Long Count

Step One: Using the “Maya Long Count Conversion” chart above, convert each place value in the date 12 . 18 . 14 . 11 . 16  into days. Add these five numbers together and subtract 2 to get the total number of days. A formula has been provided below to help you get started. You will need to do your calculations on another sheet of paper.

12*Baktun + 18*Katun + 14* Tun + 11*Uinal + 16*Kin – 2 = ________days

Step Two: Record your birth date (in the Gregorian method). If you were born prior to January 1, 1988, calculate the number of days from the day you were born to December 31, 1987 (Answer A). If you were born on or after January 1, 1988, calculate the number of days from this date to the day you were born (Answer B). Keep in mind that leap years have an extra day. The chart below will help you with the number of days for each month. Record this number.

Educator How-To: Calculate your birthday in Maya Long Count

Note: The following are leap years and have a total of 366 days (a 29th day in February): 1960, 1964, 1968, 1972, 1976, 1980, 1984, 1988, 1992, 1996, 2000, 2004, 2008, and 2012.  All non-leap years have 365 days.

Step Three:  If you calculated answer A, subtract this number from the Step One answer. If you calculated answer B, add this number to the answer from Step One. Record this number..

Step Four:
Convert the number of days since the Maya Fourth Creation to your birth date in Maya Long Count using the “Maya Long Count Conversions” chart.

To calculate your birthday:

How many whole baktuns are there in C days?  This number (we’ll call it D) goes in the baktun position.
How many days are left over from C after you subtract the number of days in D baktuns? Call this E.
How many whole katuns are in E days? Call this number F and put it in the katun position.
How many days are left over from E after you subtract the number of days in F katuns? Call this number G.
How many whole tuns are in G days?  Call this number H and put it in the tun position.
How many days are left over from G after you subtract the number of days in H tuns? Call this number I.
How many whole uinals are in I days? Call this number J and put it in the uinal position.
How many days are left over after you subtract the number of days in J uinals? This is the number of kin in your birthday.

Fill in the spaces using your calculations, and check your answer here by plugging it into the applet.

Educator How-To: Calculate your birthday in Maya Long Count