The Rumi calendar ( Turkish Rumi Takvim ) is based on the Julian calendar, with the Hijrah, the emigration of Muhammad from Mecca to Medina in 622, incipient solar calendar. It was introduced during the Tanzimat period, and was in effect from 1840 to 1926 in the Ottoman Empire and the Republic of Turkey. For non- official matters continues to be the Hijri calendar was used.
In 1677, a proposal by the Supreme Director of Finance Hasan Pasha was implemented, after which one should from this point every 33 years skip a year to compensate for the difference between Hijri and the Julian calendar. 1740, the beginning of the year was transferred by order of the Director of Finance Atıf Efendi from Muharram to March. On March 13, 1840 of the Julian calendar that was used up to this point only in financial matters, introduced as part of the Tanzimat period as Rumi calendar for the official sector. As it was in 1871 failed again omit a year was built between the Rumi and the Gregorian Calendar, a difference of 585 years in January and February and 584 years for the rest of the data.
On March 1, 1917, the Rumi calendar was changed from the Julian to the Gregorian calendar. On February 15, 1332 ( Julian Hijri count) followed by omission of 13 days March 1, 1333 (1917 ). Furthermore, he was transferred to the beginning of the year to 1 January. Thus went from there to the years of the two calendar with a difference of 584 years completely parallel.
Law No. 698 beginning of 1926, the Gregorian calendar as a so-called "International Calendar " was ( beynelmilel takvim / بین الملل تقویم ) introduced. The month of the Rumi calendar were taken.
In early 1945, the month names Teşrin -i Evvel, Teşrin -i Sani, Kanun -ı Evvel and Kanun -ı Sani were changed by Act No. 4696 within the meaning of the language in Turkisierung Ekim, Kasim, Aralık and Ocak.