Las Vegas is about 15 times smaller than Istanbul.

Istanbul is approximately 5,343 sq km, while Las Vegas (map shows its 26 named neighbourhoods; the area covers the whole city) is approximately 367 sq km, making Las Vegas 6.88% the size of Istanbul.
Tip: This to-scale comparison of Istanbul vs. Las Vegas 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.