How do you convert a Hijri date?
How does the Hijri calendar work?
The Hijri calendar is a lunar calendar. A year has twelve months of 29 or 30 days, so a Hijri year is about 11 days shorter than a solar year. Years are counted from 622, the year of the Prophet Muhammad's migration (Hijra) from Mecca to Medina. Most Ottoman documents are dated in this calendar.
This tool uses the arithmetical (tabular) form of the Hijri calendar. In the Ottoman Empire the start of a month was often set by sighting the crescent moon, so the date in a document can differ from the calculated date by one day, rarely two. If the document gives the day of the week, compare it with the result to find the right day.
How do you convert a Rumi date?
When and why was the Rumi calendar used?
The Rumi (Mali, or fiscal) calendar was adopted for official business in 1840, during the Tanzimat reforms. Its first day, 1 Mart 1256, corresponds to 13 March 1840 in the Gregorian calendar. It is based on the Julian calendar and its year begins in March. The year number continued from the Hijri year of its adoption but then advanced with the solar year, so the difference from the Gregorian year stayed constant.
- For the months March to December, add 584 to the Rumi year.
- For January and February the year has not yet turned, so add 585.
- The difference in days is 12 days before 1900 and 13 days after. Many converters always use 13 days and are one day off for 19th-century dates.
What changed in the Rumi calendar in 1917?
In 1917 the difference in days was removed. The day after 15 Şubat 1332 became 1 Mart 1333, so 13 days were dropped from the calendar. From then on, the day and month of a Rumi date are the same as in the Gregorian calendar. From 1918 the year also began on 1 January. The Rumi calendar was replaced by the Gregorian calendar at the beginning of 1926 under a law passed in 1925.
How are Gregorian dates before 1582 calculated?
The Gregorian calendar we use today came into force in October 1582. Earlier events are given in the Julian calendar, as in history books. This tool also calculates dates before 15 October 1582 in the Julian calendar. For example, the conquest of Constantinople on 29 May 1453 fell on a Tuesday.
Month names
What do the month names in Ottoman documents mean?
| HIJRI MONTHS | RUMI MONTHS | MODERN NAME |
|---|---|---|
| 1. Muharram (Muharrem) | Mart | March |
| 2. Safar (Safer) | Nisan | April |
| 3. Rabi al-Awwal (Rebiülevvel) | Mayıs | May |
| 4. Rabi al-Thani (Rebiülahir) | Haziran | June |
| 5. Jumada al-Ula (Cemaziyelevvel) | Temmuz | July |
| 6. Jumada al-Akhira (Cemaziyelahir) | Ağustos | August |
| 7. Rajab (Recep) | Eylül | September |
| 8. Sha'ban (Şaban) | Teşrinievvel | October |
| 9. Ramadan (Ramazan) | Teşrinisani | November |
| 10. Shawwal (Şevval) | Kânunuevvel | December |
| 11. Dhu al-Qa'da (Zilkade) | Kânunusani | January |
| 12. Dhu al-Hijja (Zilhicce) | Şubat | February |
Hijri and Rumi months do not correspond to each other; the table only places their names side by side. The Rumi column starts with March because the Rumi year opened in March. In brackets are the Turkish forms of the Hijri months, as they appear in Ottoman Turkish documents.
References
- Reingold, E. M., & Dershowitz, N. (2018). Calendrical calculations: The ultimate edition. Cambridge University Press.
- Unat, F. R. (1959). Hicrî tarihleri milâdî tarihe çevirme kılavuzu (3rd ed.). Türk Tarih Kurumu.
