Hijri Date Converter & Islamic Calendar

The History and Establishment of the Islamic Hijri Calendar

The Hijri Calendar (التقويم الهجري), also known as the Islamic Lunar Calendar, is the sacred chronometric system that governs Islamic religious observances, including the determination of Ramadan fasting, the two Eids (Eid al-Fitr and Eid al-Adha), the sacred pilgrimage (Hajj), and annual Zakat anniversaries.

Prior to the calendar's formalization, early Arabs identified years by major historical occurrences (such as Am al-Fil, the Year of the Elephant). In 16 AH (638 CE), during the caliphate of Sayyiduna Umar ibn al-Khattab (RA), administrative dispatches arrived from Abu Musa al-Ash'ari noting confusion over undated official documents. Caliph Umar convened the senior Companions of the Prophet ﷺ—including Ali ibn Abi Talib and Uthman ibn Affan (RA)—to establish a unified calendar epoch.

After deliberating whether to date from the Prophet's ﷺ birth or his receiving of divine revelation, Sayyiduna Ali (RA) proposed dating the calendar from the Hijrah (the historic migration of Prophet Muhammad ﷺ from persecution in Makkah to the establishment of the first Islamic commonwealth in Madinah in 622 CE). The Hijrah was unanimously adopted as the turning point that separated truth from falsehood and marked the birth of the global Muslim civilization.

Quranic Foundations of the 12 Lunar Months

The Holy Quran explicitly establishes the lunar year as the divinely ordained measure of time for humanity:

"Indeed, the number of months with Allah is twelve [lunar] months in the register of Allah [from] the day He created the heavens and the earth; of these, four are sacred. That is the correct religion, so do not wrong yourselves during them." (Surah At-Tawbah 9:36)

In Surah Yunus (10:5), Allah SWT describes the cosmic creation of the sun and moon as celestial timekeepers:

"It is He who made the sun a shining light and the moon a derived light and determined for it phases - that you may know the number of years and account [of time]. Allah has not created this except in truth." (Surah Yunus 10:5)

The Four Sacred Months (Al-Ashhur Al-Hurum)

Within the twelve lunar months, Almighty Allah designated four months as particularly inviolable and sacred (Hurum). In these months, acts of aggression are strictly prohibited, and spiritual devotions earn magnified rewards:

1. Dhul-Qi'dah (ذو القعدة - 11th Month): The month of resting from travel and preparing for the Hajj pilgrimage.
2. Dhul-Hijjah (ذو الحجة - 12th Month): The month of the Great Pilgrimage (Hajj), the Day of Arafah (9th), and Eid al-Adha (10th).
3. Muharram (المحرم - 1st Month): The opening month of the Islamic year, containing the blessed Day of Ashura (10th Muharram).
4. Rajab (رجب - 7th Month): The isolated sacred month preceding Sha'ban, commemorating the miraculous Night Journey and Ascension (Al-Isra wal-Mi'raj).

The Twelve Months of the Islamic Calendar in Order

Moon Sighting (Ru'yah) vs. Astronomical Calculation (Hisab)

In contemporary Islamic practice, two primary methodologies exist for confirming the start of each lunar month:

• Physical Moon Sighting (Ru'yat al-Hilal): Following the literal instruction of the Prophet Muhammad ﷺ: "Fast when you see the crescent moon and break your fast when you see it." (Sahih al-Bukhari). If clouds obstruct visibility on the 29th evening, the current month is completed as 30 days.
• Astronomical Calculations (Umm al-Qura Standard): Using accurate lunar orbital physics to determine when conjunction occurs and whether the crescent moon sets after sunset.

Because local atmospheric visibility varies, our converter provides a Regional Adjustment Selector (-2 to +2 days) so you can perfectly calibrate dates according to your local national moon-sighting authority.

Sunnah Fasting and the White Days (Ayyam al-Beed)

The Islamic lunar calendar is intimately connected with recommended voluntary worship (Nawafil). The Prophet Muhammad ﷺ strongly encouraged observing voluntary fasting on the White Days (Ayyam al-Beed / أَيَّام البِيض), which occur on the 13th, 14th, and 15th nights of every Islamic lunar month when the full moon (Badr) illuminates the night sky.

Abu Dharr (RA) narrated that the Messenger of Allah ﷺ instructed: "If you fast any part of the month, then fast on the thirteenth, fourteenth, and fifteenth." (Sunan an-Nasa'i). Fasting three days of every lunar month is spiritually equivalent to fasting an entire lifetime because every good deed is multiplied tenfold by Allah's infinite mercy.

Frequently Asked Questions About the Hijri Calendar

1. How do you convert a Gregorian year to a Hijri year mathematically?

An approximate conversion formula is: Hijri Year ≈ (Gregorian Year - 622) × (33 / 32). For precise daily conversions, Julian Day Number (JD) algorithms are utilized to map the exact synodic lunar orbital cycles.

2. Why does Ramadan occur earlier every year on the solar calendar?

Because the lunar year is 10 to 11 days shorter than the 365-day solar year, every Islamic date moves approximately 10 to 11 days earlier in the Gregorian calendar each successive year, completing a full cycle across all seasons every 33 years.

3. What does "AH" stand for in Islamic dates?

"AH" stands for the Latin phrase Anno Hegirae ("In the year of the Hijrah"), corresponding to the Arabic abbreviation (هـ) designating years counted from the Prophet's ﷺ migration to Madinah.