How Many Days Are in A Month?

There are 12 months in a year, and each month can have 28, 29, 30, or 31 days. It’s something we’ve all learned, but have you ever wondered why this is the case?

Let’s start with the shortest month, February. Most of the time, February only has 28 days. But every four years, in what we call a leap year, February gets an extra day and has 29 days. But why does February get this special treatment? The answer lies in the way we measure time.

Number of days in a month:

  1. The first month, January, features 31 full days.
  2. The second month, February, usually has 28 days. However, it has 29 days during what we refer to as leap years.
  3. The third month of the year, March, has 31 days.
  4. The fourth month on the calendar, April, has 30 days.
  5. The fifth month of the year, May, comes with 31 days.
  6. The month of June, which is the sixth month, has 30 days.
  7. The seventh month, July, has 31 days in total.
  8. The eighth month, August, also has 31 days.
  9. The ninth month, September, consists of 30 days.
  10. The tenth month, October, has 31 days.
  11. The eleventh month, November, has 30 days.
  12. The final and twelfth month, December, includes 31 days.

Solar Year and Leap Year: Why We Have 12 Months in 1 year

We base our calendar year on the solar year, which is the time it takes for the Earth to orbit the sun once. But the Earth doesn’t orbit the sun in exactly 365 days. It’s closer to 365.25 days. To make up for this quarter of a day, we add an extra day to our calendar every four years, making that year a leap year with 366 days instead of the standard 365.

The History of February

Now, you might be wondering, why we add this extra day to February, making it 29 days long during leap years, instead of just having a 31-day month like many others? The reason has historical roots. The Roman king Numa Pompilius, who reigned between 715-673 BC, is credited with creating the 12-month calendar. To avoid any association with even numbers, which were considered unlucky, the king tried to make all the months odd-numbered days. But to reach the 355 days of the lunar calendar, one month ended up with an even number, and February, being the last month in their calendar, was the unlucky recipient of the short straw.

The Rest of the Months

Now, what about the rest of the months? Why do some have 30 days and others have 31? Again, it’s thanks to the Romans. Originally, the Roman calendar had 10 months, starting with March and ending with December. January and February were added later by Numa Pompilius. To balance the total number of days in a year, he alternated between 30 and 31 days in the subsequent months. July and August, named after Julius Caesar and Emperor Augustus, both have 31 days each to honor their greatness.


In conclusion, the number of days in each month is a combination of astronomy and history. The Earth’s journey around the sun determines the length of a year, while historical figures and beliefs have shaped the individual months. So, next time you’re flipping your calendar to a new month, take a moment to appreciate the thousands of years of science and history that have gone into that simple page turn.

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