Istanbul Province (Turkish: İstanbul ili) is a province located in north-west Turkey. It has an area of 5,343.02 km² and a population of 13,854,740. It is surrounded by the provinces of Tekirdağ to the west, Kocaeli to the east, the Black Sea to the northern part and the Sea of Marmara to the south. The Bosphorus (Boğaziçi) Strait divides the province in two parts: the European side and the Asian side. Roughly 3.85 million people live on the Asian side in 2010 census, and 9.4 million on the European side.
The capital of the province is the city of Istanbul, which, since 2004, has the same boundaries as the province.
^"Büyükşehir Belediyesi Kanunu". Türkiye Büyük Millet Meclisi (in Turkish). 10 July 2004. Retrieved 2010-11-30. Bu Kanunun yürürlüğe girdiği tarihte; büyükşehir belediye sınırları, İstanbul ve Kocaeli ilinde, il mülkî sınırıdır. (On the date this law goes in effect, the metropolitan city boundaries, in the provinces of İstanbul and Kocaeli, are those of the province.)