Why Does February Have Only 28 or 29 Days?

“Why does February have only 28 or 29 days in the month?” A question which the staff of the Newton Falls Public Library had not considered is always a fun one to answer. First we looked at Chase’s Calendar of Events. The book contains 4000 birthdays, 1400 historical anniversaries, 650 national and international holidays, 160 religious holidays, and thousands of other notable days, but does not say why February has fewer days than other months. It does remind the reader that February is Library Lovers’ Month.


Encyclopedias are excellent sources of basic information. In the library’s copy of World Book Encyclopedia 2007, we found an entry about February [pg. 60]. Before 700 B.C. calendars only had 10 months. The Roman ruler, Numa Pompilius added January and February, with February being the last month of the year. The month only had 28 days until “Julius Caesar gave it 29 in standard years and 30 every fourth year. According to tradition, the Roman emperor Augustus took one day off February to add to August, the month named after him.”



We were still curious about why this month had fewer days than the others. The New York Public Library Desk Reference states on the cover that it is “the most valuable answer book you will ever own,” so we thought we would see what it had about the calendar. In the section on The Development of the Roman/Julian/Gregorian Calendar [pg. 13] it states that “Julius Caesar rejected the Roman lunar calendar in favor of a solar one . . . The solar year was made up of 365 ¼ days. A leap day was added every 4 years to maintain the balance between the calendar and the seasons.” Included with this article is a chart showing the development of calendars by Romulus in 738 B.C., King Numa Pompilius, Council of Decemvirs, Julius Caesar, Augustus Caesar, to Gregory XIII in 1582. In the 10 month Romulus calendar, Decembris is the shortest month with 29 days. The calendars of King Numa Pompilius and the Council of Decemvirs have months that are 28, 29, or 31 days long. The succeeding calendars adjusted the number of days in a year and in months, until the Gregorian calendar finally left only February with 28 or 29 days.