Riga is about 11 times smaller than Hanoi.

Hanoi is approximately 3,360 sq km, while Riga is approximately 304 sq km, making Riga 9.05% the size of Hanoi.
Tip: This to-scale comparison of Hanoi vs. Riga 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.