Istanbul is about 3.1 times smaller than Beijing.

Beijing is approximately 16,411 sq km, while Istanbul is approximately 5,343 sq km, making Istanbul 32.56% the size of Beijing.
Tip: This to-scale comparison of Beijing vs. Istanbul uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.