Originally Posted by Red__Zed

The 12/21/12 date is based on counting days. Leap years are irrelevant, they are two completely different calendars.

The Mayan baktun is 400 tuns. Each tun is 360 days, meaning a baktun was 144,000 days long.

August 11, 3113 BC was the first day on the Mayan calendar. Counting the days from there, we get our 12/21/12 as the date of the baktun change, meaning the first number in the Mayan calendar will change from 12 to 13, making it 13.0.0.0.0. The last time this happened was on September 18, 1618, where it changed to 12.0.0.0.0.



Sincerely,

Capt. Buzzkill