The Hijri calendar (also known as the Islamic calendar or Arabic calendar) is a lunar calendar consisting of 12 months based on the phases of the moon. It was established during the reign of Caliph Umar ibn al-Khattab, with the starting epoch being the Hijra — the migration of Prophet Muhammad (PBUH) from Mecca to Medina in 622 CE. Each Hijri year has approximately 354 or 355 days, making it about 10-11 days shorter than the Gregorian solar year. The Hijri calendar is used primarily to determine Islamic holidays, rituals, and events such as Ramadan, Hajj, Eid al-Fitr, and Eid al-Adha.

The key differences are: (1) Basis: Hijri is a lunar calendar (moon-based), while Gregorian is a solar calendar (sun-based). (2) Year length: A Hijri year has ~354 days; a Gregorian year has ~365 days. (3) Month length: Hijri months are 29 or 30 days based on moon sighting; Gregorian months are 28-31 days fixed. (4) Year count: The Hijri year 1446 AH roughly corresponds to 2024-2025 CE. (5) Seasonal alignment: Because the Hijri year is shorter, Islamic months shift backward by about 10-11 days each Gregorian year, cycling through all seasons over approximately 33 years.

The Hijri calendar holds immense religious significance because many Islamic obligations and observances are tied to it. These include: Ramadan (the 9th month of fasting), Hajj (pilgrimage during Dhul-Hijjah), Eid al-Fitr (1st of Shawwal), Eid al-Adha (10th of Dhul-Hijjah), Ashura (10th of Muharram), and the sacred months (Muharram, Rajab, Dhul-Qi'dah, Dhul-Hijjah) during which warfare is traditionally prohibited. Muslims worldwide rely on the Hijri calendar for scheduling these religious duties and celebrations.

Hijri months alternate between 30 and 29 days in a standard pattern: Muharram (30), Safar (29), Rabi' al-Awwal (30), Rabi' al-Thani (29), Jumada al-Awwal (30), Jumada al-Thani (29), Rajab (30), Sha'ban (29), Ramadan (30), Shawwal (29), Dhul-Qi'dah (30), Dhul-Hijjah (29). In a leap year (occurring 11 times in a 30-year cycle), Dhul-Hijjah has 30 days instead of 29, making the year 355 days. However, actual month lengths can vary slightly based on physical moon sighting, which may shift a day in some regions.

This converter uses a widely-adopted arithmetic algorithm based on the Kuwaiti / Umm al-Qura calculation method, which provides accurate results for dates within the Islamic era (from 1 AH onward). The computed dates are accurate to ±1 day for most dates, which is consistent with the inherent variability of the lunar calendar due to regional moon-sighting differences. For religious observances that require precise moon sighting, always consult your local Islamic authority or mosque for the officially announced dates.

The Hijri calendar relies on physical sighting of the new crescent moon (hilal) to determine the start of each month. Because the moon's visibility depends on geographic location, atmospheric conditions, and local sunset times, different countries may sight the crescent on different evenings. For example, Ramadan may begin a day earlier in Saudi Arabia than in some parts of South Asia or Africa. Additionally, some Islamic organizations use astronomical calculations to predetermine dates, while others strictly adhere to visual sighting, leading to occasional variations.

In the Islamic calendar, a new day begins at sunset (Maghrib time), not at midnight as in the Gregorian system. This means that the night precedes the daylight hours. For example, Friday night in Islamic terms is actually the night before Friday's daylight period (i.e., what Gregorian calendars would call Thursday evening). This is why Islamic congregational prayers, Ramadan fasting times, and Eid celebrations are all tied to sunset and moon sighting.

The current Hijri year is approximately 1446 AH (as of 2024-2025 CE). The Hijri year count starts from the Hijra (migration) of Prophet Muhammad (PBUH) from Mecca to Medina, which corresponds to July 16, 622 CE in the Julian calendar. To estimate the Hijri year from a Gregorian year, you can use the formula: Hijri Year ≈ (Gregorian Year − 622) × 33 ÷ 32. Our converter above provides the precise conversion for any specific date.

There are four sacred months (Al-Ashhur al-Hurum) in the Islamic calendar, as mentioned in the Quran (Surah At-Tawbah 9:36). They are: Muharram (1st month), Rajab (7th month), Dhul-Qi'dah (11th month), and Dhul-Hijjah (12th month). During these months, warfare was traditionally forbidden, and good deeds are believed to carry greater reward. Many Muslims choose to fast, give charity, and increase worship during these sacred periods, especially during Muharram (including the Day of Ashura on the 10th) and the first ten days of Dhul-Hijjah.

Manual conversion is complex due to the lunar nature of the Hijri calendar. A simplified approximation: Gregorian Year ≈ Hijri Year × 0.97 + 622. For a more precise conversion, you need to account for the specific month and day using astronomical tables or algorithms that calculate the Julian Day Number as an intermediate step. Our online converter above handles all these calculations instantly, saving you from complex manual computation. For academic or programming purposes, the Kuwaiti algorithm is the most widely referenced method for programmatic Hijri-Gregorian conversion.