Quick Answer
A Hijri year runs 354 or 355 days, about 10.88 days shorter than a Gregorian year, so the two drift apart and Ramadan moves through the seasons. This converter uses the tabular Islamic calendar with the epoch that best fits the published Umm al-Qura tables: exact on 41 of 62 reference dates, never more than one day out.
Converting between the Hijri and Gregorian calendars is arithmetic, but the answer is not a single fact. The Hijri month begins when a new crescent is judged to have appeared, and different authorities judge that differently — so two people can be living the same day under two different dates. The converter above gives you a date and, unusually, tells you which calendar produced it and how far out it can be.
How the Hijri Calendar Counts Time
The Hijri calendar is purely lunar. Twelve lunar months make a year of 354 or 355 days, with no leap month to pull it back into line with the seasons. A Gregorian year is about 365.24 days, so the two drift apart by roughly 10.9 days every year. That drift is the single most useful thing to understand about it: Ramadan is not a summer month or a winter month, it moves through the whole solar year and returns to the same season after about 33 Hijri years.
The arithmetic in one line. A tabular Hijri year is 354 11/30 days, so thirty years contain exactly 10,631 days — eleven of those thirty years carry a 355th day. Against the Gregorian year of 365.2425 days, that leaves a gap of about 10.88 days a year.
The month lengths alternate. Odd-numbered months carry 30 days and even-numbered months 29, and in a leap year the twelfth month takes a thirtieth day. That produces the table below, which is what the converter enforces when it refuses an impossible date.
| # | Month | Days | Known for |
|---|---|---|---|
| 1 | Muharram | 30 | The Hijri new year; Ashura falls on the 10th |
| 2 | Safar | 29 | — |
| 3 | Rabi’ al-Awwal | 30 | The Prophet’s birth is marked on the 12th |
| 4 | Rabi’ al-Thani | 29 | — |
| 5 | Jumada al-Awwal | 30 | — |
| 6 | Jumada al-Thani | 29 | — |
| 7 | Rajab | 30 | One of the four sacred months |
| 8 | Sha’ban | 29 | — |
| 9 | Ramadan | 30 | The month of fasting |
| 10 | Shawwal | 29 | Eid al-Fitr falls on the 1st |
| 11 | Dhu al-Qi’dah | 30 | Sacred month |
| 12 | Dhu al-Hijjah | 29 or 30 | Hajj; Eid al-Adha on the 10th |
Those are the lengths of the tabular calendar, the arithmetic version used for conversion. An observed month is whatever the crescent turns out to allow — 29 or 30 days — which is exactly why a converted date and an observed date can disagree.
Which Calendar Produced Your Answer
Most date converters print one date and say nothing about where it came from. That hides a real problem, because there is no single Hijri calendar to convert to.
Saudi Arabia publishes the Umm al-Qura calendar, which is computed rather than sighted. Its criterion has not been constant. R.H. van Gent of Utrecht University documents the astronomical rules the Umm al-Qura calendar has used, and they have been rewritten three times in living memory:
| In force | The rule for starting a month |
|---|---|
| 1392–1419 AH (16 Mar 1972 – 16 Apr 1999) | “When the astronomical new moon occurs less than 3 hours after Saudi midnight… the lunar month begins at the previous sunset” |
| 1420–1422 AH (from 17 Apr 1999) | “On the 29th of the month, the next day is the first day of the [new] month if the moonset is after sunset at Mecca” |
| 1423 AH onward (from 15 Mar 2002) | “(1) The geocentric conjunction occurs before sunset. (2) The moon sets after the sun.” |
Rules quoted from van Gent, The Umm al-Qura Calendar of Saudi Arabia — astronomical rules.
The consequence is easy to miss and worth stating plainly: a Hijri date converted for 1995 was produced by a different rule from one converted for 2015. A converter that never names its method cannot tell you that, and a birth certificate issued under one rule does not automatically agree with a converter running another.
Do not treat a converted date as an observed one. Many communities begin a month on a local sighting rather than a calculation. Van Gent records that around Ramadan and Dhu al-Hijjah the dates observed by different Muslim communities “are found to differ by one, two or even three days”. For anything that must match an official record — a visa, a certificate, a court filing — use the date on the document, not a converted one.
How to Use the Hijri Date Converter
- Pick the calendar your date is already written in.
Choose Gregorian if you are reading a passport, a certificate or an ordinary wall calendar. Choose Hijri if the date names a month such as Ramadan or Muharram and carries an AH year.
- Enter the day, month and year.
The month list swaps between the two calendars when you change direction, so you are never picking September while the tool reads Ramadan. Impossible dates are refused rather than silently rolled forward — there is no 30 Safar, and the tool says so instead of quietly giving you 1 Rabi’ al-Awwal.
- Read the converted date, then the line beneath it.
The headline is the date in the other calendar. The tag underneath repeats the date you typed, so a shared link always carries both. The panel also gives the weekday, the numeric form and the distance from today.
- Check the “calendar used” cell.
It says Tabular Islamic on every answer. That is deliberate: the number is only as good as the rule behind it, and the rule is named rather than assumed.
- Switch to Hijri age if you want a birthday rather than a date.
The second mode reads the same fields as a date of birth and returns your age in Hijri years, months and days, plus when your next Hijri birthday falls.
How Accurate This Converter Is
This is the part most converters leave out, so here is the measurement rather than a claim.
The tool uses the tabular Islamic calendar. To choose its epoch, three candidates were run against the 62 Umm al-Qura reference dates van Gent publishes for 1420–1450 AH — 1 Muharram and 1 Ramadan of each of those 31 years. The epoch shipped here is the one that fits best:
| Epoch tried | Exact matches | Within one day | Worst case |
|---|---|---|---|
| Astronomical (JDN 1948438) | 0 of 62 | 21 of 62 | 2 days |
| Civil (JDN 1948439) | 21 of 62 | 62 of 62 | 1 day |
| Civil + 1 day (JDN 1948440) | 41 of 62 | 62 of 62 | 1 day |
So inside 1420–1450 AH this converter lands exactly on two thirds of the published Umm al-Qura month starts and is never more than a single day away from the rest. Outside that window the arithmetic still runs, but nothing has been checked against a published table, and the tool says so on the answer rather than letting you assume otherwise.
See the one-day gap for yourself. In van Gent’s table of principal Islamic days, 1 Ramadan 1448 AH begins on 8 February 2027 and 1 Muharram 1448 on 16 June 2026. Convert both above: Ramadan comes back exactly, and Muharram comes back as 17 June 2026 — one day later. That is not a bug in the arithmetic, it is the gap this whole section is about, and it is why the tool names its calendar on every answer.
Hijri Age and Why It Runs Ahead
Because a Hijri year is about 10.9 days shorter, a Hijri age climbs faster than a Gregorian one. The gap is not trivial: after roughly 32 Gregorian years a person has lived about 33 Hijri years, and the two counts separate by a further year every three decades or so.
The age mode counts whole Hijri years, then months, then days, borrowing real month lengths rather than an average — so it never reports a month component outside 0 to 11, and never a negative day. It also gives the next Hijri birthday in both calendars, which is the practical question: a Hijri birthday moves about eleven days earlier in the Gregorian year each time it comes round.
The same shortened year is why the lunar calendar matters for obligations measured in years rather than seasons. Zakat becomes due after a full lunar year of ownership, not a solar one, which is a difference of about eleven days on every cycle — the Zakat Calculator works from that same lunar year.
Mistakes That Change the Answer
- Assuming there is one Hijri date for a given day.
There is not. A computed calendar, a local sighting and a neighbouring country’s announcement can all differ, by up to three days around Ramadan and Dhu al-Hijjah.
- Converting an official date and expecting a match.
A document issued in 1995 was dated under a rule that Saudi Arabia replaced in 1999 and replaced again in 2002. Convert for interest; quote the document for anything official.
- Typing an AH year into the Gregorian field.
1447 read as a Gregorian year converts to the ninth century AH and looks absurd rather than wrong, which is how the mistake survives. The direction control and the year hint both exist to prevent it.
- Expecting a 31st.
No Hijri month has 31 days, and the even-numbered ones have 29. A converter that silently rolls 30 Safar into 1 Rabi’ al-Awwal has quietly changed your date; this one refuses it.
- Treating a Hijri birthday as fixed in the Gregorian year.
It moves about eleven days earlier annually. A birthday in early spring one year is in late winter a few years later.
Hijri Date Converter: FAQ
Press “Use today’s date” in the converter above and it will read your device’s date and convert it. It is computed in your browser, so it is always current rather than whatever was true when the page was last cached. Remember that the answer is the tabular calendar’s; if your local mosque announced a month start on a sighting, its date may be a day either side.
Because you are almost certainly comparing two different calendars. Saudi Arabia’s Umm al-Qura calendar is computed, many communities go by local sighting, and converters use various arithmetic approximations of both. Van Gent records observed dates differing by “one, two or even three days”. This page states which calendar produced its answer so the comparison is at least an honest one.
354 days in a common year and 355 in a leap year. Eleven of every thirty years are leap years, so thirty Hijri years contain exactly 10,631 days — an average of about 354.37 days. The extra day is added to Dhu al-Hijjah, the twelfth month.
Roughly one extra year for every 33 years lived. Because the Hijri year is about 10.9 days shorter, someone who has lived about 32 Gregorian years has lived about 33 Hijri years. The age mode above works it out exactly rather than by that rule of thumb, counting whole Hijri months and days.
The converter accepts Hijri years from 1 AH and Gregorian years from 1 CE, and the arithmetic runs across all of them. Be careful what you do with the result: only 1420–1450 AH has been checked against published Umm al-Qura dates, and for the early centuries the tabular calendar is a reconstruction rather than a record of what anyone actually observed.
The ninth. It carries 30 days in the tabular calendar, though an observed Ramadan can run 29 or 30 days depending on the sighting that ends it. In 2026 and 2027 the tabular start of Ramadan 1448 falls on 8 February 2027; announced start dates commonly land a day either side of a computed one.
Anno Hegirae — “in the year of the Hijra”. Year 1 AH begins with the Prophet’s migration from Mecca to Medina. Because the Hijri year is shorter, AH years do not map one-to-one onto CE years: a single Gregorian year usually contains parts of two Hijri years, which is why the converter asks for a full date rather than just a year.
No, and neither is any other converter. Within 1420–1450 AH this one matches 41 of the 62 published Umm al-Qura reference dates exactly and the rest to within one day, which is good enough for genealogy, planning and curiosity. For a passport, a visa or a legal filing, use the date printed on the document — it was issued under a specific rule, and possibly one that has since been replaced.
