Time is something we take for granted. It just exists – we don’t really question why or how. Your birthday may be in the summer, the week always starts with Sunday, and for some reason February is super short and sometimes has an extra day. This is just the way of the world.

However, this wasn’t always the case. Ancient civilizations, like the Babylonians, Egyptians, and Romans, had a large role to play in the way we tell time and in the modern calendar we use today!

Hour Glass

History of Calendars Timeline

Do you have a few minutes? Check out this timeline to learn more about the evolution of the calendar, from full moons in ancient Mesopotamia to funny calendars that were released during the COVID-19 pandemic.

  • 2510 BC

    2510 BC http://narmer.info/listy/kalend_en.htm

    The Egyptians created their own calendar, which used the moon’s cycles and a star named Sirius to keep track of time. The Egyptian calendar had 12 months just like the one used in Mesopotamia, but they had 5 extra days in their year.

  • 738 BC

    738 BC https://en.wikipedia.org/wiki/Roman_calendar

    The first Roman calendar was introduced by King Romulus. This calendar had only 10 months, starting in March and ending in December. A lunar year had 354 days, but since the Romans believed even numbers were lucky, they changed things around so that each month had an even number of days. This caused the seasons to be out of sync year after year!

  • 500 BC

    500 BC https://www.liuliusa.com/collections/crystal-art-chinese-zodiac

    Your zodiac sign is said to provide insight into your personality and values. Some even believe it can predict the future. The Chinese lunar calendar, which revolves around the zodiac and astronomy, first appeared in China in the 5th century BC.

  • 500 BC

    500 BC https://c.tadst.com/gfx/600×337/istock-545593812.jpg?1

    Many people think of “Doom’s Day” (December 21, 2012) when they think of the Mayan calendar, and there was even made a movie made about it. According to the BBC News, however, this was “a big understanding.” The calendar ended in 2012 simply because it was the end of one cycle and the beginning of another.

  • 499 BC

    499 BC https://sites.google.com/

    Mesopotamia, Rome, and Egypt had calendars, so the Babylonians wanted to follow suit with one of their own. Their lunar calendar had a 13th month every two or three years and eventually inspired the Jewish calendar still in use today.

  • 400 BC

    400 BC https://www.worldhistory.org/article/833/the-athenian-calendar/

    The Greeks had many lunisolar calendars they used to keep track of time. The Athenian calendar, also known as the attic or civil calendar, was the most common, but the Greeks also created the Olympiad, Seasonal, Conciliar, and Metonic calendars. Each one was based on the cycle of the moon and stars as well as solar equinoxes.

  • 70 BC

    70 BC https://www.chabad.org/library/article_cdo/aid/55194/jewish/About-the-Jewish-Calendar.htm

    The Hebrew calendar was created in Israel. This calendar is lunisolar and is heavily based on mathematics. Today, the Hebrew calendar is still used for Jewish religious observations.

  • 46 BC

    46 BC https://www.britannica.com/biography/Julius-Caesar-Roman-ruler

    The Julian calendar was used in Rome. This brand new calendar was developed by Julius Caesar since there was a lot of corruption in the original Roman calendar. In fact, political figures would purposefully extend or shorten the days in a year in order to keep allies and enemies in or out of office.

  • 400 AD

    400 AD https://en.hope.or.jp/2019/09/13/ethiopian-calendar

    Rather than using the moon, the Ethiopians tracked the progression of time using the sun. Their calendar has 13 months and is 7 years behind the calendar that we use today in America.

  • 622 AD

    622 AD https://printablecalendarblanks.com/extraordinary-2020-calendar-with-islamic-dates/

    The Hijiri calendar was used to track Islamic, Muslim, or Arabic holidays and rituals. Like other calendars, it has 12 months, only these are broken into sacred months and non-sacred months. The Hijiri calendar doesn’t have any leap months or days.

  • 1000 – 1100

    1000 – 1100 https://www.persiapage.com/persian-calendar-1400/

    Persia (modern day Iran) used what is known as the Persian calendar. This calendar has since been modified many times. Today, the calendar used in Iran and Afghanistan begins each year on the vernal equinox, which is around March 21st.

  • 1500 – 1521

    1500 – 1521 https://www.thoughtco.com/what-is-the-aztec-calendar-stone-169912

    The Aztecs in central Mexico used a carved stone to keep track of time. The sun god, Tonatiuh, was right in the center, and he was surrounded by many other figures in Aztec mythology and astrology. The Aztec solar year had 18 months, each with 20 days. Each century was only 52 years.

  • 1582

    1582 http://www.surinenglish.com/lifestyle/201710/06/october-1592-that-never-20171006103346-v.html

    Pope Gregory XIII wasn’t a huge fan of the Julian calendar that was previously used in Rome. He wanted the calendar to reflect Catholic ideas, so he made the switch the Gregorian calendar. This is what we use today in America.

  • 1752

    1752 https://en.wikipedia.org/wiki/Adoption_of_the_Gregorian_calendar

    The United States adopted the Gregorian calendar. At this point, 10 countries were already using this system including Italy, France, Germany, Portugal, and Switzerland.

  • 1777

    1777 https://www.bostonglobe.com/ideas/2013/06/01/the-daily-planner-american-history/WncDRG5hq7B9m0w3cE5jkM/story.html

    The first planner was created by Robert Aitken in the United States, a year after the signing of the Declaration of Independence. This planner showed each week on its own page and was designed to keep track of business records.

  • 1851

    1851 https://www.thecottagejournal.com/discover-history-behind-advent-calendar/

    Religious families used advent calendars to track feasts that were meant to honor saints. One of the first decorative advent calendars was used in Germany and had 34 small candles attached to cardboard. Now we fill up our advent calendars with small treats and chocolates.

  • 1891

    1891 http://posterandprintshack.com/coca-cola-calendar-with-hilda-clark-1901/

    After the Industrial Revolution, paper calendars started to be used to advertise new businesses. Coca-Cola was one of the pioneers of custom merchandise, and today their original calendars are valued as high as $18,500.

  • Early to Mid-1900s

    Early to Mid-1900s https://www.icollect247.com/item/167560/Louisville-KY-Evening-Post-Calendar-1909-Paperboy-Giveway

    Newspapers started advertising with paper calendars to get more subscriptions. The one pictured here was an advertising calendar used by The Louisville Evening Post.

  • 1920s

    1920s https://web.soldsie.com/

    Business was thriving in the 1920s, leading to the first desk calendars ever made. These were often carved from wood and sat on the boss or CEO’s desk.

  • 1943

    1943 https://www.riverratantiques.com/listing/548290950/vintage-1943-drug-store-calendar-wwii

    During World War II, drugstores would hang calendars that showed important dates and notifications about the war. These calendars wouldn’t feature weather predictions, however, since the government believed that information could give the enemy an advantage.

  • 1950s

    1950s https://clickamericana.com/topics/

    Pin-up girls became popular after World War II. Artists would draw the pin-up calendars by hand, with each month showing a woman posing in a sultry position while wearing either a swimsuit or fashionable outfit.

  • 1960s

    1960s https://clickamericana.com/topics/home-garden/vintage-calendar-towels-from-retro-kitchens

    While the men were fighting in the Vietnam War, the women at home could use these calendar towels to dry the dishes after preparing meals and to keep up with their children’s schedules.

  • 1960s – 1980s

    1960s - 1980s https://www.ebay.com/itm/224447284205?hash=item344219c3ed:g:eG8AAOSwTnhgjqNT

    Car culture was on the rise! Manufacturers like Ford, Chevrolet, and Mercedes showcased their latest and greatest models on 12-month car wall calendars.

  • 1994

    1994 https://exaud.com/mobile-gaming-part-i

    The IBM Simon is considered one of the earliest smartphones in use. It had a touchscreen and was one of the first cell phones to also have a built-in calendar.

  • 2009

    2009 https://edu.gcfglobal.org/en/google-tips/getting-started-with-google-calendar/1/

    Google Calendar was released for public use. It can be accessed on desktop or through a mobile app on Android or iOS platforms. This digital calendar is an easy way to get reminders about upcoming events, birthdays, and holidays.

  • 2013

    2013 http://www.sci-news.com/archaeology/science-worlds-oldest-calendar-scotland-01230.html

    A team of archaeologists from the University of St. Andrews uncovered the world’s oldest calendar while working on the Crathes Castle in Scotland. This calendar wasn’t like the cute puppy calendars you can buy today, but rather, was 12 giant holes in the ground that mirrored the moon’s phases.

  • 2019

    2019 https://www.fastcompany.com/90289375/this-mega-calendar-helps-you-plan-the-next-10-years-of-your-life

    Do you know what your plans are 10 years from now? Track them by using this mega calendar, which has enough space for a decade. It’s a giant dry erase board that costs $199.99.

  • 2021

    2021 https://www.amazon.com/Calendar-Lockdown-Quarantine-Isolation-Distance/dp/B08P1H4G61

    COVID-19 was a defining moment that changed the world. To add some levity to the situation, many humorous products came out including these 2021 calendars, which give a clever nod to the toilet paper shortage that occurred during the pandemic.

Who Made the First Calendar? https://kids.britannica.com/

Who Made the First Calendar?

Who Made the First Calendar? https://kids.britannica.com/

Historians believe timekeeping goes as far back as the Neolithic period, but actual calendars weren’t around until the Bronze Age in 3100 BC. The Sumerians in Mesopotamia made the very first calendar, which divided a year into 12 lunar months, each consisting of 29 or 30 days.

The Sumerian calendar was very different from the one we use today. Here’s how:

  • One year had 360 days
  • A day was divided into 12 hours – 6 “daytime” hours and 6 “nighttime” hours
  • Wet and dry seasons were observed
  • There were no weeks
  • Each month had 29 or 30 days
  • Holy days were observed on the 7th and 15th of the month
  • An extra month was added every four years

Astronomy was huge when it came to keeping track of time. The Sumerians used the sighting of the first full moon to mark a new month. Hundreds of years later, the Egyptians, Babylonians, and other ancient civilizations created their own calendars, using the rotation of the sun, moon, and stars to figure out how much time had passed.

Overall, these time-tracking techniques may seem outdated, but they’re not that different from the paper wall calendars and phone calendars we use today!

Did you know?

Farming was a big reason why calendars were invented. The change in seasons was important since it would affect the livelihood of livestock and crops. This could make the difference between life or death for ancient civilizations!

What is the Oldest Calendar in the World? https://www.bbc.com/

What is the Oldest Calendar in the World?

What is the Oldest Calendar in the World? https://www.bbc.com/

Although, the Sumerians are credited as the first to track time, some historians believe the Europeans had a system that could be even older! A team of researchers from the University of St. Andrews found 12 large pits in Aberdeenshire, Scotland that mirrored the moon’s phrases. These holes are estimated to be 10,000 years old and may be the oldest “calendars” in the world.

This discovery proves that the history of calendars is always changing. Time will tell what else we uncover in the future!

Who Invented the Modern Calendar? https://www.quora.com/

Who Invented the Modern Calendar?

Who Invented the Modern Calendar? https://www.quora.com/

The modern calendar is a hodgepodge of astronomy, religion, and politics from many different ancient civilizations. Mesopotamia, Babylonia, Greece, Egypt, and Rome all contributed in some way to the calendar we use today.

Nowadays, a majority of countries use the Gregorian calendar, which was invented by Pope Gregory XIII in 1582. The Gregorian calendar was seen as a way to spread Catholicism throughout Europe. Before then, people believed in and worshipped gods and goddesses.

This calendar was created simply because Pope Gregory wanted to celebrate Easter on the correct day, and the Julian calendar that had previously been used in Rome was about 10 days off.

Regardless of all these changes, you shouldn’t assume that the Gregorian calendar is 100% accurate. It’s based on Earth’s trip around the sun, which isn’t always a clean 365 days. In fact, experts believe we’ll have 366 days in the year 4909!

Did you know?

Britain made the switch from the Julian calendar to the Gregorian calendar in 1752. This caused them to lose out on 11 days, leading to what some historians believe was a massive riot.

How Did the 12 Months Get Their Names?

The 12 months of the year get their names from ancient Rome. Each name was based on some aspect of Roman culture, whether it was their customs, political figures, mythology, or use of Latin phrases.



Where it got its name: Janus – the god of new beginnings

Janus is the perfect representation of the first month of a new year. He had two faces, one that looked into the past and one into the future. Janus was also seen as the god of doors, which represents pursuing new opportunities and embracing change.

Fun fact: Half of the adults in the United States make New Year’s resolutions every January.



Where it got its name: Februalia festival – an annual fest that promoted health and fertility

The Februalia festival lasted all month in Rome and was held as a way to banish evil spirits. The wealthy would skip work and spend the entire month praying and meditating. Wouldn’t it be amazing if we got all of February off work today?

Fun fact: Black history month was proposed by educators at Kent State University in February 1969.



Where it got its name: Mars – the god of war

Winter interrupted wartime in Rome, and battles wouldn’t resume until the weather was more tolerable. This explains why March was named after Mars, the god of war.

Fun fact: An estimated 13 million pints of Guinness are consumed in honor of St. Patrick’s Day every year.



Where it got its name: Unclear. Some historians believe it comes from Aphrodite, the goddess of love and beauty. Others think it comes from the Latin word aperio, which means “to open (bud).”

Historians are not sure how April got its name, but regardless, it’s seen as a month of beauty and growth. If the Romans were in the midst of war, they would even plant balsam and ebony trees during this month to signify victories in battles.

Fun fact: 95% of primary and secondary schools in the United States celebrate Earth Day on April 22nd.



Where it got its name: Maia – the goddess of fertility and growth

In ancient Rome, Maia oversaw the growth of plants. Horticulture was a significant part of life in their society. They would use plants and flowers for food, drinks, medicine, cosmetics, aromatherapy, and even religious worship.

Fun fact: According to the U.S. Census Bureau, Mother’s Day was first observed on May 10, 1908.



Where it got its name: Juno – the goddess of love and marriage

Midsummer was important in ancient Rome as it was a time where powerful families would arrange marriages. June was a very popular month for these weddings, which is why it was named after the goddess of love and marriage.

Fun fact: $20 million is spent every year on Father’s Day, which is observed on the third Sunday of June.



Where it got its name: birth month of Julius Caesar – Roman general who was famously assassinated in 44 BC

It only made sense for Julius Caesar to be represented somewhere in the Roman calendar. After all, he is credited with creating the Julian system of telling time in Rome.

Fun fact: An estimated 150 million hot dogs are eaten every year on the Fourth of July in the United States.



Where it got its name: Augustus Caesar – Roman emperor who was the great nephew of Julius Caesar

Not to be outdone by his great uncle, Augustus’s name also inspired a month of the year. He was a respected leader in Rome just like Julius Caesar and was even able to restore the city to its former glory following the war.

Fun fact: 43% of students in the United States go back to school in August.



Where it got its name: Septem – Latin word for “seven”

Wait, isn’t September the ninth month? Why is it named after the Latin word for “seven?” This can be explained by the fact that September was the seventh month in the original Roman calendar. The name just kind of stuck.

Fun fact: September is the most common birthday month in America.



Where it got its name: Octo – Latin word for “eight”

The original Roman calendar only had 10 months. October was the eighth month in a year at that time, and for some reason, the name wasn’t changed when Rome made the switch to the Julian calendar.

Fun fact: October is the most popular month for weddings in the United States.



Where it got its name: Novem – Latin word for “nine”

Even though November is the eleventh month, it was the ninth month in the original Roman calendar. As Rome made the switch to the Gregorian calendar, no one bothered to change the names. Now the numbers are all jumbled up in the modern calendar we use today!

Fun fact: 46 million turkeys are eaten every year on Thanksgiving, which is observed on the fourth Thursday of November.



Where it got its name: Decem – Latin word for “ten”

December was the tenth month in the Roman calendar. History and tradition were important in Rome, which could explain why they wanted to hold onto some of the names from their original calendar.

Fun fact: The average American spends $942 every year on Christmas gifts.

Why Don’t All the Months Have the Same Number of Days?

Why Don’t All the Months Have the Same Number of Days?

Why Don’t All the Months Have the Same Number of Days?

The months aren’t all the same number of days due to the rotation of the moon. Ancient Romans based each month on the time between two new moons, which is 29.5 days. Since this number doesn’t divide evenly into the 365.2421 days that are in a year, the months are always a different length.

Months with 28 days (29 days on leap years):

  • February

Months with 30 days:

  • April
  • June
  • September
  • November

Months with 31 days:

  • January
  • March
  • May
  • July
  • August
  • October
  • December

About 59% of the months in a year have 31 days, 33% have 30 days, and then there’s February, which only has 28 days or 29 days. The pattern alternates between shorter and longer months, with the exception being July and August which each have 31 days. Hello, longer summer!

Why is February So Short?

Why is February So Short?

Why is February So Short?

February is short because of leap years. In ancient Rome, they used the Earth’s revolution around the sun to track a year, which isn’t a perfect 365 days. It’s actually 365 days, 5 hours, 48 minutes, and 46 seconds (365.2421 days). That extra time adds up every four years, which is why February gets an extra day.

So why does February get less days instead of June or November? This can be attributed to Roman superstition! King Numa Pompilius divided the 12 cycles of the moon across 12 months. Since February was a month of spiritual purification, the shorter number of days kept evil spirits on Earth for less time.

Did you know?

The Hebrew, Chinese, and Buddhist calendars have leap months instead of leap days.

Where Did the 7 Day Week Come From?

Where Did the 7 Day Week Come From?

Where Did the 7 Day Week Come From?

The 7-day week was first found in the Babylonian calendar. It represents the time it takes for the moon to transition between each of its phases, starting and ending at the crescent moon.

The days of the week are a mash-up of many different languages and cultural ideas. Here’s where they got their names!

  • Sunday – from the Latin solis, which means “Sun’s Day”
  • Monday – from the Latin lunae, which means “Moon’s Day”
  • Tuesday – named after Tiw, the Viking god of law
  • Wednesday – named after Woden, the Viking god of gods
  • Thursday – named after Thor, the Viking god of war
  • Friday – named after Frida, the Viking god of love
  • Saturday – named after Saturn, the Roman god of agriculture

So why do we have a five-day workweek? The answer comes from 20th century New England where overworked men were demanding a sabbath, or a couple days of rest. The Great Depression sealed the deal since a two-day weekend meant shorter hours and less unemployment.

Did you know?

The word “weekend” was first used in 1879. It was found in an English magazine called Notes and Queries.

Why Do Calendars Start on Sundays? https://spiritualray.com/egyptian-sun-god-ra

Why Do Calendars Start on Sundays?

Why Do Calendars Start on Sundays? https://spiritualray.com/egyptian-sun-god-ra

There’s a religious and historical reason why Sunday is the first day of the week. Historians believe both ancient Egypt and Rome had a role to play in this fact.

In ancient Egypt, Sunday was seen as the “day of the sun” and was spent honoring the sun god, Ra. Worship was seen as a suitable way to start a new week.

Ancient Rome may have also contributed to Sunday as the first day of the week. The Romans believed that the week started with the sun (Sunday) and moon (Monday) and ended with Saturn (Saturday).

Why Are There 24 Hours in a Day? https://www.kdwebdesigns.com/

Why Are There 24 Hours in a Day?

Why Are There 24 Hours in a Day? https://www.kdwebdesigns.com/

The 24 hour day was observed in ancient Egypt in 2510 BC. The Egyptians used shadow clocks and sundials to measure the daytime and nighttime in 12 hour increments. In the summer, the days would be longer. In the winter, the nights were longer.

Do you want to see the full history of the calendar? Watch this video!

How Many Major Holidays Are in a Year?

How Many Major Holidays Are in a Year?

How Many Major Holidays Are in a Year?

In the United States, we observe ten federal holidays including: New Year’s Day, Martin Luther King Jr. Day, Presidents’ Day, Memorial Day, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving, and Christmas.

There are many other holidays that we look forward to every year as well. You may give out candy for Valentine’s Day and Halloween, or hunt for eggs on Easter Sunday. It just depends on your individual beliefs and traditions.

Why Are Calendars Important?

Why Are Calendars Important?

Why Are Calendars Important?

We’d probably go crazy if we didn’t have a universal way of keeping track of time. People would roll into the office whenever they wanted, schools wouldn’t have a regulated start and end time, and you’d have no language for telling your friends when to meet you for lunch. Talk about chaos!

Calendars keep our society moving forward. They’re a way to keep us all on the same page. Time flies by, so be sure you cherish every moment!

Stats for Success

Stats for Success

35% of people name Saturday as their favorite day of the week.

Stats for Success

Only 15% of U.S. companies offer a 4-day workweek.

Stats for Success

48% of people feel like they don’t have enough time to do what they want to do.

The Bottom Line

The way we tell time has evolved over the years, and no culture seemed to think of it in the same way. The calendar is still not perfect, but it’s so steeped in history and tradition, we don’t bother questioning its inaccuracies. No matter what, appreciate every moment and use your calendar to stay organized! You’ll be happy you did.


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