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The Enoch calendar is an ancient calendar described in the pseudepigraphal Book of Enoch.

It divided the year into four seasons of exactly 13 weeks each. Each such season consisted of two 30-day months followed by one 31-day month. Each season began on a Sunday; since the first month had 30 days, the second month began on a Tuesday; since the second month had 30 days, the third month began on a Thursday.

Calendar expert John Pratt wrote that "The Enoch calendar has been criticized as hopelessly primitive because, with only 364 days, it would get out of sync with the seasons so quickly: in only 25 years the seasons would arrive an entire month early. Such a gross discrepancy, however, merely indicates that the method of intercalation has been omitted."[1]

E. G. Richards noted a system of intercalation that would make the Enoch calendar as accurate as the Gregorian calendar.[2]

Pratt proposed what he considers a better system. Adding an extra week at the end of every seventh year (called by Pratt a "Saturday year") makes the calendar as accurate as the Julian Calendar. Then, defining a "Great Year" to be a period of 364 years, just as a year in the Enoch calendar is a period of 364 days, Pratt says "In every set of five Great Years, two of the extra weeks ending the 28-year-cycle would be skipped, one in the third and another in the fifth Great Year." This makes the calendar more accurate than the Gregorian calendar.

See Also[]

Qumran Calendar a similar calendar


  1. John Pratt, Review of Mapping Time:, The Calendar and Its History, by E. G. Richards, American Mathematical Monthly, volume 107, number 1, January, 2000
  2. E. G. Richards, Mapping Time: The Calendar and Its History, Oxford University Press, 1998.