Hijri to Gregorian Converter: Free Islamic Date Calculator

Free two-way Islamic date calculator

Convert an Islamic or Arabic calendar date to the Gregorian calendar—or change a Gregorian date to Hijri—in seconds. The calculator uses the tabular Islamic civil calendar and works entirely in your browser.

A Hijri to Gregorian converter is useful whenever an Islamic date must be matched with a civil date used by schools, workplaces, government offices, travel systems or digital calendars. It is equally useful in reverse: a Gregorian to Hijri converter can show the Islamic date associated with a birthday, historical event, appointment or planned journey.

Hijri calendar

A lunar calendar of 12 months and normally 354 or 355 days.

Gregorian calendar

A solar civil calendar of 365 days, with 366 days in a leap year.

Expected variation

Calculated and officially observed Hijri dates may occasionally differ by one day.

How to use this Hijri and Gregorian calendar converter

Convert Hijri to Gregorian

1. Keep the Hijri → Gregorian tab selected.
2. Choose the Islamic month.
3. Enter the Hijri day and year.
4. Select Convert to Gregorian.

The result displays the weekday, Gregorian day, month and year. This is the quickest way to convert an Islamic date to a Gregorian date without using a printed comparison table.

Convert Gregorian to Hijri

1. Open the Gregorian → Hijri tab.
2. Select a date from the date field.
3. Select Convert to Hijri.

The result gives the calculated Hijri day, month and AH year. The “Use today” button makes this a quick Islamic date finder as well as a date converter.

What is the Hijri calendar?

The Hijri calendar—also called the Islamic calendar, Muslim calendar or Arabic lunar calendar—is a system of 12 lunar months. Its era is counted from the Hijrah, the migration of Prophet Muhammad ﷺ and the early Muslim community from Makkah to Madinah in 622 CE. The calendar was formally organized during the caliphate of Umar ibn al-Khattab, while Muharram was retained as the first month of the year.

A Hijri year contains approximately 354 or 355 days. Because it follows lunar months rather than the solar seasons, it is about 10 or 11 days shorter than a Gregorian year. Ramadan, Hajj and other Islamic observances therefore move through the seasons over a cycle of roughly 33 solar years.

Britannica describes the Islamic calendar as a 12-month calendar used for religious purposes and notes that its year contains 354 or 355 days. The U.S. Naval Observatory also documents the widely used arithmetic form of the calendar, which employs a 30-year cycle with 11 leap years. That arithmetic model is what makes instant date calculation possible.

What is the Gregorian calendar?

The Gregorian calendar is the solar calendar now used for civil and international purposes in most of the world. It normally has 365 days divided into 12 months. A leap day is added to February in most years divisible by four, except century years that are not divisible by 400.

This leap-year rule keeps the calendar aligned closely with the Earth's journey around the sun. As a result, Gregorian months remain in broadly the same seasons, unlike Hijri months.

Hijri vs Gregorian calendar: key differences

The calendars are not competing versions of the same measurement. Each reflects a different astronomical frame. A Gregorian date identifies a position in a solar year, while a Hijri date identifies a position in a lunar year. This is why a simple rule such as “add 622” cannot produce an exact conversion.

Why can a Hijri date differ by one day?

Users sometimes compare two Islamic calendar converters and find a one-day difference. That does not necessarily mean that one website is broken. Several recognized approaches exist:

• Physical crescent sighting: A community or national authority begins the month after receiving acceptable sighting testimony.
• Astronomical criteria: A calendar may use conjunction time, moonset, elongation or calculated visibility.
• Tabular Islamic calendar: A fixed arithmetic cycle alternates month lengths and inserts leap days according to a defined rule.
• Umm al-Qura calendar: Saudi Arabia's civil calendar uses its own calculated criteria and is commonly displayed by digital services.

Crescent visibility varies with location, atmospheric conditions, season and the criteria adopted by the relevant authority. Bangladesh, Saudi Arabia, Morocco, the United Kingdom and North America may therefore announce the beginning of a month on different civil dates.

For contracts, historical research or ordinary scheduling, record the calendar system used. For worship tied to the start of a lunar month, follow the recognized authority relevant to your community rather than treating an online calculation as a moon-sighting declaration.

The 12 months of the Islamic calendar

Transliterations vary. For example, “Dhul Hijjah,” “Dhu al-Hijjah” and “Zul Hijjah” refer to the same month. Likewise, “Hijri,” “Hegira” and “Islamic” are often used in calendar-conversion searches.

How the calculator converts Islamic and Gregorian dates

The calculator does not estimate a result merely by adding or subtracting years. It converts the entered date into a continuous day count, commonly called a Julian day number, and then transforms that day count into the target calendar. This allows day, month, year and leap-cycle rules to be handled consistently.

For the Hijri side, the calculator uses the arithmetic Islamic civil calendar. In that model, month lengths follow a defined pattern and leap days are distributed through a 30-year cycle. For the Gregorian side, it applies the modern Gregorian leap-year rule. All calculations occur locally in the visitor's browser; no date is submitted to a server by this file.

Can you convert a Hijri year to Gregorian manually?

A rough year estimate can be useful when an exact day is not required:

Approximate Gregorian year = Hijri year × 0.970224 + 621.5774

For example, 1447 AH gives approximately 2025.6, meaning that 1447 AH overlaps portions of 2025 and 2026. This formula cannot identify an exact date because a Hijri year spans parts of two Gregorian years.

A reverse estimate is:

Approximate Hijri year = (Gregorian year − 621.5774) ÷ 0.970224

Use these formulas only for broad historical orientation. For a date conversion from Hijri to Gregorian—or Gregorian to Islamic—use the calculator at the top of this page.

Common reasons to convert Hijri and Gregorian dates

• Matching dates printed on Arabic birth, marriage or educational records.
• Planning travel during Ramadan, Umrah or the Hajj season.
• Finding the Gregorian date associated with an Islamic historical event.
• Adding a Hijri date to an invitation, announcement or community calendar.
• Comparing archival documents that use AH and CE date systems.
• Estimating the civil date of a future Islamic occasion before an official announcement.

Is an Arabic calendar always the Hijri calendar?

Not necessarily. The phrase “Arabic calendar” is often used online to mean the Islamic lunar calendar, but Arabic-speaking countries also use the Gregorian calendar for many civil purposes. Saudi Arabia additionally publishes the Umm al-Qura calendar, while the term “Hijri Shamsi” refers to a different solar Hijri calendar used in Iran and Afghanistan.

This calculator converts the lunar Islamic Hijri calendar, not the Persian Solar Hijri or Shamsi calendar. A search such as “convert Hijri Shamsi to Gregorian” requires a separate algorithm.

Frequently asked questions

Final guidance

A reliable Islamic to Gregorian calendar converter should do more than produce a number. It should explain which calendar model it uses and why a result may differ from a locally announced date. Use this calculator for education, planning and ordinary records, while checking official religious announcements when an act of worship depends on the confirmed beginning of a lunar month.

Sources and further reading

• U.S. Naval Observatory — The Islamic Calendar
• Encyclopaedia Britannica — Islamic calendar
• Encyclopaedia Iranica — Calendars in the Islamic period