The Islamic Calendar: All You Need to Know About the Hijri Calendar

Many in the West are so used to the Gregorian calendar, that they don’t even stop to consider how many other calendars there are in the world. In fact, according to a recent estimate, there are as many as 40 calendars in use today!

One of the most important ones is the Hijri calendar used by Muslims to mark important religious events such as Ramadan, Eid, and the annual pilgrimage to Makkah – Hajj. These all have deeply religious and historical significance. But exactly what is the Hijri calendar?

What Is the Hijri Calendar?

The Hijri calendar is the Islamic calendar that Muslims use to determine dates of religious events and observances – but it’s not the same as the widely adopted Gregorian calendar.

The Hijri calendar is purely lunar.

While there are also twelve months in the Islamic calendar, these are lunar months determined by when a new moon is sighted.

As a result, the Islamic Hijri calendar consists of 354 or 355 days and the dates of religious events can differ from year to year in the Gregorian calendar.

How Does the Moon Dictate the Hijri Calendar?

The Hijri calendar, also known as the Islamic calendar, is a lunar calendar widely used in the Muslim world to determine Islamic holy days and events. It is based on the cycles of the moon. Each month begins with the first sighting of a new crescent moon which appears after the new moon phase.

Due to these sightings, both the Islamic calendar and the lunar calendar consist of twelve months of 29 or 30 days.

The link between the Hijri calendar and the lunar calendar is an essential aspect of the Islamic faith and has significant implications for Muslims worldwide.

The Lunar Calendar vs the Solar Calendar

Both the solar and lunar calendars are ways of measuring the time that has been used by various civilizations throughout history. While the solar calendar is based on the Earth’s orbit around the Sun, the lunar calendar is based on the phases of the Moon.

The most widely used solar calendar today is the Gregorian calendar, which has 365 days in a year, as that is how long it takes for the Earth to complete a single orbit of the Sun. The year is then subsequently divided into twelve months. This calendar was introduced by Pope Gregory XIII in 1582 to replace the Julian calendar, which had a slightly shorter year.

The lunar calendar, on the other hand, is based on moon phases. It measures the length of a lunar month by tracking the amount of time it takes for the Moon to complete one orbit around the Earth.

The Muslim calendar consists of twelve months, each of which lasts for 29 or 30 days, depending on the sighting of the new moon. This sighting marks the end of one Islamic month and the start of the new month. These shorter Islamic months make the total number of days in the lunar year and the Islamic calendar year either 354 or 355 days. As a result, the Hijri year is ten or eleven days shorter than the Gregorian year.

When Was the Islamic Calendar Introduced?

Introduced way back in the year 622 CE (AKA 622 AD), we are now in the Islamic year of 1444 (as of 30th March 2023 – Gregorian date).

But how did it all start?

Before the establishment of the Islamic calendar, Arab tribes used different systems for measuring time, including different lunar and solar calendars. However, these systems were neither accurate nor consistent, which made it difficult for ancient Arabs to determine the precise dates of religious festivals.

During early Islam, in the 17th year of the Hijra (the journey of Muhammad PBUH and his followers from Makkah to Medina), there were some disputes and misunderstandings. One was about whether a man should pay someone back by Ramadan this year or the next. The other was about governors not sure whether to do something in the month of that year or the next year.

To find a solution, the Caliph at the time – Umar Ibn Al Khattab (RA) – gathered the Shura Council who settled on a unique calendar for the Ummah to follow. Unsure when their calendar should initially start, they settled on the year of the Hijra since that was when the Muslims’ situation changed. They escaped from persecution and the new Islamic era was born.

This event occurred in the year 622 CE, and thus the first year of the Hijri calendar was designated as “1 AH” (After Hijra).

Why Is the Islamic Calendar Important?

Aside from commemorating significant Islamic events, the Hijri calendar is also important as it serves as a reminder of the history of the Muslims and all they sacrificed, such as their wealth and family ties as they moved from Makkah to Madinah to preserve their religion.

The establishment of a calendar reflects the establishment of a Muslim community. After all, civilisation deserves its calendar that reflects its history.

What Are the Islamic Months?

The Islamic year starts with the first month of Muharram and is followed by: Safar, Rabi Al-Awwal, Rabi Al-Thani, Jamad Al-Awwal, Jamad Al-Thani, Rajab, Sha’ban, Ramadan, Shawwal, Dhul Qadah and finishes with Dhul Hijjah, one of the most sacred months in Islam.

Important Islamic Dates to Remember

All dates in the Hijri calendar are subject to moon sightings and so may well vary by a day or two. Nevertheless, as we are now in the year 2023, there are several important dates on the Islamic Calendar to keep in mind:

Laylat al-Isra Wal Miraj

Falling on Saturday, 18th February 2023, or the 27th day of Rajab, Laylat al-Isra Wal Miraj commemorates the night-time journey made by Muhammad (PBUH) from Makkah to the farthest mosque in Jerusalem, Masjid Al-Aqsa. This is the night in which the number of daily prayers was established.


Ramadan is the ninth month in the Hijri Calendar that falls between Wednesday 22nd March and Friday 21st April 2023. Throughout this month, Muslims fast from before dawn to sunset.

Ramadan was the month in which the first verse of the Quran was revealed to Prophet Muhammad (PBUH), hence why it is often referred to as ‘the month of the Qur’an’.

It is an intensely spiritual month where Muslims forgo worldly affairs and pleasures as much as they can and work on their relationship with their Lord – Allah (SWT). Ramadan is an opportunity to pick up positive habits and characteristics you can build on and improve until Ramadan next year.

The month closes with Laylatul-Qadr, the Night of Power, an extremely important event where righteous acts are multiplied by Allah (SWT). This is found in one of the odd nights in the final ten nights of Ramadan.

Eid Al-Fitr marks the end of Ramadan and the first day of the next month, Shawwal. Known as the festival of the breaking of the fast, this falls on Friday, 21st April 2023.

Eid Al-Adha

The second Eid celebration in the Muslim year falls on Wednesday, 28th June 2023. Known as the Festival of the Sacrifice, this celebration commemorates Prophet Ibraham’s (AS) dedication to Allah (SWT) and how he was willing to sacrifice his son until he was given a ram to sacrifice instead. Most Muslim countries mark this day in the calendar as a holiday and a time to celebrate Eid with family and the Ummah as a whole. This occasion is celebrated by sharing meat with the poor and needy and celebrating with friends and family.


Hajj is the annual pilgrimage to Makkah, which is required of every Muslim at least once in their lifetime if they are physically and financially able. The Hajj rituals mirror the sacrifice Prophet Ibrahim (AS) and his family made. Every year in this holy month, Muslim pilgrims journey to Makkah. Approximately three million Muslims from all across the world congregate for the sole purpose of worshipping our creator, Allah (SWT). In 2023, the Hajj pilgrimage takes place between Monday 26th June and Saturday 1st July.

The Day of Arafah

This marks the 2nd day of Hajj and the 9th day of Dhul Hijjah. The Day of Arafah commemorates the day when Allah perfected the religion of Islam, as well as when Prophet Muhammad (PBUH) delivered his final sermon from atop Mount Arafah. To celebrate this day, Muslims pray and repent for their sins. The Prophet (PBUH) said: ‘There is no day on which Allah (SWT) frees people from the fire more so than on the Day of Arafah’ and so it is a perfect day to ask for forgiveness.

Islamic New Year

The day after Dhul Hijjah is the first day of the next Islamic year of 1445, which will fall on Wednesday 19th July 2023.

The Day of Ashura

This is the 10th day of Muharram (‘Ashura’ means ‘tenth’ in Arabic) and falls on Thursday, 27th July 2023. For Sunni Muslims, this marks the exodus of the Prophet Musa (AS) from Egypt. On this day, Muslims engage in righteous acts. Although fasting on this day isn’t obligatory, many still choose to fast, just like Musa did to thank God for saving him and his followers by parting the Red Sea.


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