Roman Calendar by Yuen Tai


Introduction and History of Roman Calendar


Though the Roman calendar is not used today, it has close relationships with the calendars today. The names of the months in the calendars today originated from Roman Calendars. Initially, the Roman calendar only contains 10 months in a year; 6 of 30 days and 4 of 31 days; the 10 months came out to be 304 days. The Romans neglected the 61 days that fell in the middle of the winter. That was the case until the Roman ruler Numa Pompilius added 2 extra months to the calendar thus making it 12 months, with 355 days in a year.


Astronomical Basis


The Romans had a defined marker within each month, which was based on the moon. Roman months were identical to the lunar cycle; each month was divided into 3 sections. The sections were named Kalends, Nones, and Ides which corresponds with the new, first quarter, and full moon phases respectively.



                                                       Days of Ides    Days of Nones   Days of Kalends

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Days of Kalends


Out of the three sections, Kalends last for the longest, because it starts from the day when the lunar crescent was first sighted until the first quarter moon phase then it starts again after full moon phase all the way until another lunar crescent was sighted. The Romans calculated that it’ll take atleast 6 days before lunar crescent reaches the first quarter moon phase which begins the Days on Nones.


Days of Nones


Days of Nones start from the day when the moon reaches its first quarter phase until it reaches full moon.


Days of Ides


Days of Ides is when the moon reaches full moon phase.