Los Angeles is about 2.8 times smaller than Hanoi.

Hanoi is approximately 3,360 sq km, while Los Angeles (including the city proper only) is approximately 1,215 sq km, making Los Angeles 36.15% the size of Hanoi.
Tip: This to-scale comparison of Hanoi vs. Los Angeles 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.