Dating systems

This is a list of calendars, dating systems, chronologies, etc. used in Magic: The Gathering.

Argivian Reckoning
Argivian Reckoning (AR) is the primary calendar used on Dominaria (notably excepting the continent of Corondor). It sets year 0 as the year in which both Urza and Mishra were born. It only came into use many years after the time of the Brothers, and was used informally for several thousand years before an attempt was made to clarify historical facts. It is named after New Argive, a country famed for its scholars. The last time the date was explicitly mentioned or could be directly derived from the storyline (Odyssey), it was 4306 AR. With the advent of Time Spiral block, the date can be gleaned as around 4505 AR, supposing that Argivian Reckoning is still in use.

Common Era
Common Era (CE) is a dating system established by New Sumifans in Almaaz. It starts around 3035 AR.

Penregon Founding
Penregon Founding, or PF for short, is the only calender system known to be in use at the time of The Brothers' War. It sets Year 0 as the year Penregon, the capital of Argive, was founded. When Urza and Mishra were born (0 AR), the year was 912 PF.

Reckoning of the Sages of Minorad
The Reckoning of the Sages of Minorad is a calendar primarily used in Corondor. Year 1 in this reckoning begins on the anniversary of the gathering of the Sages of Minorad. It corresponds with the year 3000 of the Argivian Reckoning.

Innistrad
Dates on Innistrad are measured using the stages of the moon and the years since Avacyn's creation, commonly shortened to "Ava." There are three seasons on Innistrad: Harvest Moon (autumn), Hunter's Moon (winter), and New Moon (spring). It is unclear how long a season or a year on Innistrad lasts, although Hunter's Moon is said to be the longest and New Moon the shortest. The latest dates known for each season in-lore are the 118th of Harvest Moon in the years of Avacyn 699 and 711, the 121st of Hunter's Moon, Ava. 718, and the 116th of New Moon, Ava. 714. If the seasons are consistent each year, this would make an Innistrad year roughly as long as an Earth year.

Lumengrid
On Mirrodin, the vedalken of Lumengrid recorded time by the cycles of the sun, although it is not clear how much time passes within each cycle. Kiryk's field reports just before his capture and compleation range from 3rd cycle of the Blue sun, 10th periodic, 5th locus to 6th cycle, 5th periodic, 15th locus. There are at least 16 periodics and 15 loci in a cycle.

The Progress Engine
After the plane's Phyrexianization, Jin-Gitaxias's Progress Engine recorded dates in numeric sequences, although it is unclear what they denote. Unctus's field reports from after his compleation range from 100-23-200239.6 to 100-23-229723.3.

Ravnica
Ravnica uses the measure of Al Concordant and Zal Concordant. Al Concordant is used to measure the time before the signing of the Guildpact, while Zal Concordant is used afterwards. The events of the Guilds of Ravnica block take place in 10,076 ZC, usually referred to as ’76.

Ravnica’s calendar contains 365 days divided into twelve months, with the same number of days as Gregorian calendar. The year begins with 1 Seleszeni (March 1). The annual celebration of the Guildpact begins on 28 Zuun and extends into 1 Seleszeni.
 * 1) Seleszeni or Orzabin (March)
 * 2) Dhazo (April)
 * 3) Prahz or Prazh (May)
 * 4) Mokosh (June)
 * 5) Paujal (July)
 * 6) Cizarm (August)
 * 7) Tevnember (September)
 * 8) Golgar (October)
 * 9) Quaegar (November)
 * 10) Xivaskir (December)
 * 11) Griev (January)
 * 12) Zuun (February)

Meletian Calendar
Although the method of marking years on Theros is unknown, Meletis has developed a calendar that has been at least partially adopted in the poleis of Akros and Setessa. The calendar is composed of 12 months, each beginning with the new moon, alternating between 30 and 29 days, and named after a festival celebrated during that month. Roughly every three years, an extra 30-day month is added to the end of the year, giving Theros a 364-day year, meaning its years are likely the same length as on Earth.
 * 1) Lyokymion
 * 2) Protokynion
 * 3) Astrapion
 * 4) Polidrysion
 * 5) Thriambion (Meletis) and Iroagonion (Akros)
 * 6) Megasphagion
 * 7) Chalcanapsion
 * 8) Necrologion
 * 9) Therimakarion
 * 10) Katabasion
 * 11) Cheimazion
 * 12) Agrypnion
 * 13) Anagrypnion (occurs every three years)