Articles About Calendar (30)
What Is a Calendar?
Calendar definition and meaning: Solar and lunar, tropical and sidereal – why did humans invent calendars? Current year in Gregorian, Muslim, and Chinese calendar.
The Gregorian Calendar
The Gregorian calendar is the internationally accepted civil calendar that was first adopted in 1582.
The Julian Calendar
The Julian calendar reformed the ancient Roman calendar and consists of three cycles of 365-day years followed by a 366-day leap year. Introduced by and named after Julius Caesar in 45 BCE.
The Hindu Calendar
Hindus use this calendar to determine the dates of festivals.
The Buddhist Calendar
Buddhists use a lunisolar calendar system. How does it work?
The Islamic Calendar
Muslims around the world use the Hijri calendar. How does it work?
The Jewish Calendar
Jews use the Hebrew calendar to set the dates of religious events.
The Persian Calendar
The Persian Solar Hijri calendar is extremely accurate. Find out why.
The Chinese Calendar
The Chinese calendar is one of the oldest calendars still in use.
The Baháʼí Calendar
The Badi calendar of the Bahai (Baháʼí ) religion features a year of nineteen months. How does the calendar system work?
The Coptic Calendar
The Coptic calendar is linked to the ancient Egyptian calendar and the Julian calendar. It is used in Egypt and in the Coptic Church. How does it work?
The Ethiopian Calendar
The Ethiopian calendar is similar to the Julian calendar.
The Roman Calendar
The Roman calendar is is the grandfather of our modern calendar.
How Does the Mayan Calendar Work?
The Maya calendar consists of a system of three interlacing calendars and almanacs which was used by several cultures in Central America, most famously the Maya civilization.
The Revised Julian Calendar
The Revised Julian calendar is one of the most accurate calendar systems ever developed. How does it work, and why don't we use it?
Gregorian Calendar Reform: Why Are Some Dates Missing?
The Gregorian calendar was introduced in 1582 in some countries. The US, Canada, and the UK changed in 1752. Why were some days skipped?
Did the Mayan Calendar Predict The End?
The Mayan calendar ended one of its great cycles in December 2012, which has fueled countless predictions about the end of the world on December 21, 2012 at 11:11(UTC).
About the 12 Months
Why are there 12 months? How long are they, and what do the month names mean?
About the 7 Days
Why are there 7 days? How were the days named, and when does the week start?
What Is a Leap Year?
A leap year has 366 days, as opposed to a common year, which has 365. Nearly every four years is a Leap Year, and we add a leap day, an extra day on February 29.
What Do CE and BCE Mean?
CE is an abbreviation for Common Era and BCE is short for Before Common Era.
Calculating the Easter Date
The date of Easter Day depends on age-old approximations of the Full Moon and the March equinox.
How Accurate Are Calendars?
Our calendar does not accurately reflect the length of a tropical year, the time it takes Earth to complete a full orbit around the Sun. Why is that so and are there other calendars that do a better job?
When Did the 21st Century Start?
When did the 3rd millennium and 21st century begin: on New Year's Day 2000 or 2001? Do we count from year 1 or year 0 AD? What century are we in?
What Is a Lunar Month?
A lunar month is the time it takes the Moon to pass through all of the Moon phases, usually measured from a New Moon the next New Moon.
The Doomsday Rule
Some dates fall on the same weekday every year. Use this knowledge to calculate the weekday of any given date in your head.
Special Calendar Dates
Learn more about numerically unique calendar dates such as sequential dates, same number dates, and palindrome (reversible) dates
A Year Is Never 365 Days
A tropical year is the time it takes for the seasons to repeat, approximately 365.242189 days. It is a fraction shorter than the time it takes Earth to orbit the Sun.
When Do Decades Start?
Did the year 2020 mark the beginning of a new decade, or did the twenties begin on January 1, 2021?
How To Write and Count Roman Numerals
To write any number in Roman numerals, combine the letters I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Start with the highest number. For example, 2022 is MMXXII. MM = 2 x 1000; XX = 2 x 10; II = 2 x 1.