Why Is December the 12th Month? History and Calendar Changes Explained

Discover why December is the 12th month due to Roman calendar origins and later reforms like the Julian and Gregorian calendars.

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December is the 12th month because of historical decisions and calendar reforms. Originally, the Roman calendar started in March and had only 10 months, making December the 10th month, which is evident from its name ('Decem' means 'ten' in Latin). However, with the additions of January and February to the start of the year by King Numa Pompilius and later adjustments by the Julian and Gregorian calendar reforms, December was repositioned to be the 12th and final month of the year.

FAQs & Answers

  1. Why was December originally the tenth month? December was originally the tenth month because the ancient Roman calendar started in March and had only 10 months, with December's name derived from 'decem,' meaning ten in Latin.
  2. Who added January and February to the calendar? King Numa Pompilius added January and February to the beginning of the Roman calendar, shifting December to the twelfth month.
  3. What calendar reforms affected the position of December? The Julian and later Gregorian calendar reforms further solidified December's position as the twelfth and final month of the year.

Watch More

For more insights on calendar origins and how months evolved, explore our videos on the history of the Gregorian calendar and the role of ancient Roman kings in shaping modern timekeeping.

  1. Why Is December the 12th Month? History Behind the Calendar Change Discover why December is the 12th month by exploring the history of the Roman, Julian, and Gregorian calendars.
  2. Why Does the Year Have 12 Months? The History Behind Our Calendar Discover how the 12-month calendar originated from the Roman system and was shaped by Julius Caesar’s reforms in 45 BCE.
  3. Why Do We Have 12 Months in a Year Instead of 13? Explained Discover why the calendar has 12 months, not 13, and how the Roman Julian calendar shaped the year we use today.
  4. Why Does the Calendar Have 12 Months Instead of 13? Explained Discover why the calendar has 12 months instead of 13, based on Earth's orbit and ancient civilizations' choices.
  5. What Number Month Is December? Understanding December in the Gregorian Calendar Discover why December is the 12th month in the Gregorian calendar and learn about its significance as the year's final month.
  6. What Is the Logic Behind the 12-Month Calendar? Discover why the calendar has 12 months based on ancient lunar and solar cycles, and how the Gregorian calendar reflects this timekeeping system.
  7. When and Why Did December Get 31 Days? Explained Discover why December has 31 days, tracing its history back to Julius Caesar's Julian calendar reform in 46 B.C.
  8. Why Are There 12 Months in a Year Instead of 13? Discover why the calendar has 12 months and its alignment with Earth's orbit. Simplified timekeeping explained.
  9. Why Is January the First Month of the Year? Explaining the Calendar History Discover why January is the first month of the year and how ancient Roman calendars influenced the modern Gregorian calendar.
  10. Why Did We Stop Using 13 Months in a Calendar? Discover why the 13-month calendar was replaced by the 12-month system influenced by the Roman calendar for better alignment with lunar cycles and seasons.
  11. What Are the 12 Months of the Year? A Complete List and Explanation Learn the names and order of the 12 months in the Gregorian calendar, used worldwide for organizing dates and time.