Hanoi is about 16 times bigger than Antwerp.

Antwerp (map shows its 62 named neighbourhoods; the area covers the whole city) is approximately 208 sq km, while Hanoi is approximately 3,360 sq km, making Hanoi 1,514% larger than Antwerp.
Tip: This to-scale comparison of Antwerp vs. Hanoi 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.