HijriConv converts dates between the Hijri and Gregorian calendars and lays out Hijri months, years and the main observances for anyone planning around them, from a family fixing an Eid trip to an archivist reading a date on an old document.
Two calendars, two sources
The Umm al-Qura dates are looked up, not estimated: the month lengths for 1318 to 1499 AH come from the MIT-licensed @umalqura/core package, an implementation of the Umm al-Qura tables, and are stored in the site's own data file. Outside that span the Umm al-Qura engine returns no date at all. The tabular calendar is pure arithmetic, a 30-year cycle with eleven leap years, so it needs no table and runs for any year. It comes in two variants: the civil one counts from Friday 16 July 622, and the astronomical one starts a day earlier, so a date in an older source can be matched to whichever convention it used. Both convert through a Julian Day Number, the method the by-hand conversion guide walks through.
What a calculation cannot tell you
Neither calendar is a moon sighting. When a religious authority announces the start of a month, the announced day can differ from the calculated one by about a day, and HijriConv does not try to predict or overrule that announcement. No page here gives a religious ruling. For Ramadan, the two Eids or any other observance, follow your local authority.
Who keeps it running
One independent developer keeps HijriConv going and also looks after Fahm, HalalAtlas, BolNama and Hafiza. The 8 guides go out under the HijriConv name with no personal byline, and the author field in their structured data is the HijriConv organization. On a guide, the date reflects the most recent change to its prose.
Corrections and privacy
If a date is wrong, a conversion is off or a sentence does not hold up, please email socialreminderinfo@gmail.com. Conversion happens in your browser; the privacy page covers what, if anything, is stored.