Dates and conversion
How to Find Your Hijri Birthday, Step by Step
Convert your birth date to the Hijri calendar, add a day if you were born after sunset, and see why your Hijri birthday comes about 11 days earlier each year.
By Tahir Nasuru · · 7 min read
Your Hijri birthday is the day, month and year of your birth in the Islamic lunar calendar. To find it, convert your Gregorian birth date with a Hijri converter. If you were born after sunset, use the next day's Hijri date, because the Islamic day begins at sunset. Your Hijri birthday then comes round on the same Hijri day and month each year, which on the Gregorian calendar lands about 11 days earlier every year.
Key Takeaways
- Convert your Gregorian birth date, then add one Hijri day if you were born between sunset and midnight.
- A Hijri year is about 354 days, so your Hijri birthday moves about 11 days earlier on the Gregorian calendar each year.
- Roughly every 33 Hijri years your Hijri birthday comes back to about the same Gregorian date.
- If you were born on the 30th of a month, some years have no 30th; you choose whether to mark the 29th or the 1st of the next month.
- Converted dates are calculated; a date announced locally from moon sighting can differ by a day.
Step 1: Convert your Gregorian birth date
Start with the date on your birth certificate and convert it to Hijri. A converter such as the Hijri date converter returns the Hijri day, month and year for that Gregorian date.
Take someone born during the day on Thursday 15 March 1990. That date converts to 18 Sha'ban 1410 AH. Sha'ban is the eighth month, so this person's Hijri birthday is the 18th of the eighth month.
The converter linked above follows the Umm al-Qura calendar of Saudi Arabia. R.H. van Gent of Utrecht University describes it as a calculated lunar calendar that Saudi Arabia has used for several decades. It uses a JavaScript port of the open-source hijri-converter library, which states that it is based on the Umm al-Qura calendar and covers 1 August 1924 to 16 November 2077 (1343 to 1500 AH). A birth date before August 1924 needs a different calculation, such as the tabular Islamic calendar, and the result is an estimate.
Step 2: Check whether you were born after sunset
A Gregorian day starts at midnight. A Hijri day starts at sunset the evening before. The US Naval Observatory's Islamic observances service puts it this way: its Islamic dates "begin at sunset of the previous evening." The post on why the Islamic day begins at sunset explains the reasoning in more detail.
A Gregorian converter does not know what time you were born. It gives the Hijri date for the daytime of your birth date. So the rule is:
- Born between midnight and sunset: use the converted date as it is.
- Born between sunset and midnight: the next Hijri day had already begun. Add one day to the converted Hijri date.
The simplest way to add the day is to convert the next Gregorian date instead.
A worked example for an evening birth
Suppose a baby was born at 8:15 pm on Thursday 21 September 1995 in Karachi.
- Converting 21 September 1995 gives 26 Rabi al-Thani 1416.
- Sunset in Karachi that evening was about 6:30 pm local time (calculated with the open-source adhan library), so 8:15 pm was after sunset.
- Converting the next day, Friday 22 September 1995, gives 27 Rabi al-Thani 1416. That is this person's Hijri birthday.
A daytime birth on the same Gregorian date would have a Hijri birthday one day earlier, on 26 Rabi al-Thani.
If you were born close to sunset, look up the exact time for your birthplace on that date. The USNO's sun and moon data for one day gives sunrise and sunset for any date from 1700 to 2100. Its definition page notes that sunset is conventionally the moment the upper edge of the sun's disk is on the horizon, calculated for an ideal flat horizon. A birth within a few minutes of that time is a borderline case. Maghrib, the sunset prayer, begins at sunset, so a family that remembers whether the Maghrib adhan had been called may be able to settle it.
Step 3: Find when your Hijri birthday falls each year
Once you have your Hijri day and month, convert that date back to Gregorian for the year you want. For the person born on 18 Sha'ban 1410, the next few Hijri birthdays fall on these dates:
| Hijri birthday | Gregorian date |
|---|---|
| 18 Sha'ban 1447 | Friday 6 February 2026 |
| 18 Sha'ban 1448 | Tuesday 26 January 2027 |
| 18 Sha'ban 1449 | Saturday 15 January 2028 |
| 18 Sha'ban 1450 | Wednesday 3 January 2029 |
| 18 Sha'ban 1451 | Monday 24 December 2029 |
Each date is 10 to 12 days earlier than the one before, 11 on average. In 2029 the birthday falls twice, on 3 January and again on 24 December, because the Sha'ban of two different Hijri years, 1450 and 1451, both falls inside that Gregorian year. For an evening birth, remember that each listed day begins at sunset the evening before.
All dates in this post are calculated from the Umm al-Qura tables in the open-source hijri-converter library that this site uses. If your community starts its months from a local moon sighting, the date it observes can be a day earlier or later than the calculated one.
Why your Hijri birthday moves every year
Your Hijri birthday moves because a Hijri year is shorter than a Gregorian year. Each Hijri month follows one cycle of the moon. NASA gives the mean length of the synodic month, from new moon to new moon, as 29.53059 days. In Sahih al-Bukhari 1913, the Prophet ﷺ describes the month as "sometimes of 29 days and sometimes of thirty days."
Twelve such months add up to about 354.4 days, while a Gregorian year averages 365.2425 days. The USNO's Islamic calendar page notes that 12 lunar months are on average 11 days shorter than the civil year, so "the Islamic year shifts earlier in each civil year by about this amount." Your Hijri birthday shifts with it. The post on why Islamic dates move each year covers the same drift for Ramadan and Eid.
The drift adds up to a full cycle. Since 33 lunar years are close to 32 solar years, a Hijri birthday works its way through every season and returns near its starting point after about 33 Hijri years. For the person born on 15 March 1990, 18 Sha'ban 1443 fell on Monday 21 March 2022 and 18 Sha'ban 1444 on Friday 10 March 2023, either side of the original 15 March.
If you were born on the 30th of a month
Hijri months have 29 or 30 days, and the same month can have 30 days one year and 29 the next. If your Hijri birthday is the 30th, some years will not have that date.
Take someone born on Friday 7 January 2000, which converts to 30 Ramadan 1420. In 1447, Ramadan has 30 days in the calculated calendar, so the birthday falls on Thursday 19 March 2026. In 1448, the calculated Ramadan has only 29 days: 29 Ramadan is Monday 8 March 2027 and 1 Shawwal follows on Tuesday 9 March.
There is no religious rule for this. It is the same situation as a 29 February birthday in a Gregorian common year. Some people mark the last day of the month and others the first day of the next; either is a personal choice. For Ramadan in particular, the local announcement of Eid decides how many days the month actually had in your community.
Your age in Hijri years
Because Hijri years are shorter, your age in Hijri years is higher than your Gregorian age, by about one year for every 33. To work it out, subtract your Hijri birth year from the Hijri year of the date you are checking, then subtract one more if your Hijri birthday has not yet come that year.
On Monday 9 November 2026 (29 Jumada al-Awwal 1448), the person born on 18 Sha'ban 1410 is 36 in Gregorian years. In Hijri years: 1448 − 1410 = 38, but 18 Sha'ban 1448 is still ahead (26 January 2027), so they are 37. The post on how old you are in Hijri years goes into the calculation and its uses.
The Quran ties the moon to the counting of years: in a translation of the meaning of Surah Yunus 10:5 (Sahih International), the moon's phases were set "that you may know the number of years and account [of time]."
Common questions
Why do two converters give me different Hijri birthdays?
Converters can use different calendars. One may follow Umm al-Qura, another the tabular Islamic calendar, and another may apply a manual adjustment of a day. And no converter knows your time of birth, so an evening birth entered without the extra day gives a result one day early. The post on why Hijri converters disagree by a day explains the main causes. Pick one method and keep using it, so your birthday does not jump between sources.
Does my Hijri birthday ever fall on my Gregorian birthday?
It lands within a few days of your Gregorian birthday about once every 33 years. Between those years it moves through the whole Gregorian calendar.
Find your own Hijri birthday
Open the date converter and enter your Gregorian birth date. If you were born after sunset, enter the next day's date instead. Write down the Hijri day and month, and check the Islamic months page if the month name is unfamiliar. Then switch the converter to Hijri-to-Gregorian and enter your Hijri day and month with next year's Hijri year to see which Gregorian date your next Hijri birthday falls on.
