How Many Weeks Are in A Month?

There are 12 months in a year, and each month can have about 4, 4.3, 4.5 or 5 weeks. Ever wondered why this is so?

Let’s simplify: 4 weeks equate to 28 days, the usual length of February in a non-leap year. Meanwhile, 4.3 weeks, the length of February in a leap year, equals 29 days. The months that have 4.5 weeks are 30 days long, while those with 5 weeks last for 31 days. This breakdown allows us to visualize the length of each month in terms of weeks.

  1. First month, January: 5 weeks, 31 days.
  2. Second month, February: Usually 4 weeks, 28 days. During leap years, it has 4.3 weeks, 29 days.
  3. Third month, March: 5 weeks, 31 days.
  4. Fourth month, April: 4.5 weeks, 30 days.
  5. Fifth month, May: 5 weeks, 31 days.
  6. Sixth month, June: 4.5 weeks, 30 days.
  7. Seventh month, July: 5 weeks, 31 days.
  8. Eighth month, August: 5 weeks, 31 days.
  9. Ninth month, September: 4.5 weeks, 30 days.
  10. Tenth month, October: 5 weeks, 31 days.
  11. Eleventh month, November: 4.5 weeks, 30 days.
  12. Twelfth and final month, December: 5 weeks, 31 days.

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

Our calendar year is based on the solar year, the time it takes for the Earth to orbit the sun once. But the Earth doesn’t orbit the sun in exactly 52 weeks. It’s closer to 52.18 weeks. To make up for these extra 0.18 weeks, we add an extra week to our calendar every four years, making that year a leap year with 53 weeks instead of the standard 52.

The History of February In Weeks

Why do we add this extra week to February, making it 4.3 weeks long during leap years, rather than just having a 5-week month like many others? The reason dates back to the Roman king Numa Pompilius, who reigned between 715-673 BC, and 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 weeks. But to reach the 50 weeks 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 in Weeks

What about the rest of the months? Why do some have 4.5 weeks and others have 5? It’s thanks to the Romans again. 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 weeks in a year, he alternated between 4.5 and 5 weeks in the subsequent months. July and August, named after Julius Caesar and Emperor Augustus, both have 5 weeks each to honor their greatness.


In conclusion, the number of weeks 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.

Leave a Reply

Your email address will not be published. Required fields are marked *