Seoul is about 1.4 times smaller than Austin.

Austin (map shows its 70 named neighbourhoods; the area covers the whole city) is approximately 829 sq km, while Seoul is approximately 605 sq km, making Seoul 73.04% the size of Austin.
Tip: This to-scale comparison of Austin vs. Seoul 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.