Hijri to Gregorian Date Conversion (and Back): Method and Tables

To convert a date from Hijri to Gregorian, or from Gregorian to Hijri, accurately you need the Umm al-Qura calendar table, not a formula, because a Hijri month is either 29 or 30 days long depending on the moon. The fastest way is the Hijri Date Converter below: choose the direction, enter the date and the result appears instantly with the weekday.

This guide explains how the two calendars differ, how the Umm al-Qura calendar works, when the quick formula is good enough and when it is wrong, and gives ready tables for the start of upcoming Hijri years and the dates of Ramadan and the two Eids.

How Do the Hijri and Gregorian Calendars Differ?

The Hijri calendar is lunar: each month starts with the new crescent moon, and a year has 12 months totalling 354 or 355 days. The Gregorian calendar is solar, with 365 days, or 366 in a leap year. That gap of about 11 days a year is the source of every conversion difficulty.

The Hijri era counts from the Prophet Muhammad's ﷺ migration (Hijra) from Makkah to Madinah in 622 CE. Caliph Umar ibn al-Khattab adopted it as the official calendar around 17 AH, and although the Hijra took place in Rabi al-Awwal, Muharram was made the first month of the year.

Because the Hijri year is shorter, Hijri occasions move about 11 days earlier every Gregorian year, so Ramadan passes through every season in roughly 33 years, as the chart in the next section shows.

Why Do Ramadan and the Eids Move Every Year?

The chart shows that Ramadan 1441 AH began on 24 April 2020, and Ramadan 1448 AH is expected to begin on 8 February 2027, then jump to December in 1452 AH (26 December 2030). The jump is not an error: in that year Ramadan starts before the previous Gregorian year has ended.

Dates are calculated with the Umm al-Qura calendar; the official dates are confirmed after the moon sighting and can differ by one day. To follow the time left live, use the Ramadan countdown, the Eid al-Fitr countdown and the Eid al-Adha countdown.

What Is the Umm al-Qura Calendar?

The Umm al-Qura calendar is the official Hijri calendar of Saudi Arabia, prepared by King Abdulaziz City for Science and Technology (KACST). It fixes the start of every month in advance using astronomical calculation for Makkah: if, on the evening of the 29th, the moon sets after the sun and the new moon (conjunction) happened before sunset, the new month starts the next day; otherwise the month runs to 30 days.

Because of this rule, the Hijri date of any day can be known years ahead, and it is the calendar printed on government documents and contracts in the Kingdom. Religious occasions such as the start of Ramadan, Shawwal and Dhu al-Hijjah are confirmed after the crescent is sighted, so an announcement can differ from the calculated calendar by a day.

How Many Days Are in Each Hijri Month?

There is no fixed pattern in Umm al-Qura; the length of every month is calculated astronomically. For example, the months of 1448 AH have these lengths:

They add up to 355 days, so 1448 AH is a long ("leap") year in Umm al-Qura. This is what makes manual conversion hard: you cannot assume the months alternate between 30 and 29 days as in the arithmetic (tabular) Islamic calendar, which adds 11 leap days every 30 years and can differ from Umm al-Qura by a day or two.

Start of Upcoming Hijri Years

This table helps when you work out yearly periods such as rent, contracts or the zakat year. 1 Muharram is Islamic New Year:

How to Convert a Date by Hand (Approximate Method)

For a quick estimate of the year without a tool, these two formulas come close:

Worked Example

1. 1To find the Gregorian year of 1448 AH: 1448 × 0.97 = 1404.6, then 1404.6 + 622 = 2026.6, meaning most of the year falls in 2026 and the rest in 2027.
2. 2The exact calculation confirms it: 1 Muharram 1448 AH is 16 June 2026, and the year ends on 5 June 2027.
3. 3But for a specific day such as 12 Rabi al-Awwal 1449 AH, the formula is not enough. The converter gives the exact answer: Saturday 14 August 2027.

Examples of Common Date Conversions

Common Mistakes When Converting Dates

• Assuming a fixed difference: the gap between the calendars grows by about 11 days a year, so you cannot add a fixed number of days.
• Mixing Hijri calendars: some sites use the arithmetic calendar or another country's calendar, which can differ by a day. In Saudi Arabia the reference is Umm al-Qura.
• Ignoring when the day starts: in Islamic practice the day begins at sunset, so the night before Friday starts on Thursday evening, while civil calendars change the date at midnight.
• Entering day 30 of a 29-day month: that date does not exist, and the converter warns you instead of returning a wrong result.
• Working out age from the year difference only: your Hijri age is not the same as your Gregorian age; read how to calculate your age in Hijri.

When Do You Need to Convert a Date?

• Filling in government or bank forms that ask for a Hijri or Gregorian date.
• Checking the expiry date of an ID, residence permit (iqama) or passport written in the other calendar.
• Working out an exact age in both calendars with the Hijri age calculator.
• Setting dates for contracts, rent and the zakat year, which is counted in Hijri years.
• Planning holidays, occasions, travel and Umrah dates.

Frequently Asked Questions

Sources

• Umm al-Qura calendar — official site
• Islamic calendar — Wikipedia
• Dates in the tables are calculated with the Umm al-Qura tables built into modern browsers, the same ones the CalcWisee converter uses.