Interactive chronology tool
Long Count
Calculator
Measure deep time through five nested cycles—and connect a Maya Long Count position with elapsed days and a Gregorian date.
01 Enter a Long Count
Set the five positions
Values are ordered from the largest cycle to the single day.
01 Enter elapsed days
Days to Long Count
Count forward from the GMT correlation anchor.
Correlation used
GMT 584,283 · proleptic Gregorian dates
02 Read the result
Long Count
13.0.0.0.0 1,872,000 elapsed days(13 × 144,000) + (0 × 7,200) + (0 × 360) + (0 × 20) + 0 = 1,872,000
Five positions, one continuous chronology. Each coefficient records a nested span of days.
Units of deep time
From one day to a baktun
K’in
1 dayThe smallest Long Count unit. K’in is associated with “day,” “sun,” and “time.”
Uinal
20 daysTwenty k’in form one uinal, the first step upward in the sequence.
Tun
360 daysEighteen uinal—not twenty—form a tun, keeping this cycle close to a solar year.
Katun
7,200 daysTwenty tun form one katun, a period of approximately twenty years.
Baktun
144,000 daysTwenty katun form one baktun, a span of roughly 394 solar years.
Method & notation
Why the third position is different
The Long Count mostly advances by twenties, but the tun contains 18 uinal: 18 × 20 = 360 days. This mixed-radix structure is why a normalized uinal position runs from 0 to 17 while the neighboring positions run from 0 to 19.
For arithmetic, this tool treats the GMT anchor as elapsed day 0. Maya creation inscriptions frame the beginning of the current era at the cycle position 13.0.0.0.0; the coefficient sequence reaches 13.0.0.0.0 again after 1,872,000 days, on December 21, 2012 under this correlation. Era context therefore matters.
Learn from the source