How big is South Korea really?
South Korea covers 100,295 km² (38,700 sq mi). On the usual world map (the Mercator projection) it is drawn about 1.54 times bigger than it really is.
See South Korea at its true size on the map →True size vs the map
Both drawn at the same scale. The map keeps shapes but swells everything away from the equator.
South Korea in numbers
Why the map gets South Korea wrong
South Korea lies around 36°N. A Mercator map stretches distances there by about 1.24 times in every direction, so areas come out roughly 1.55 times too big near its middle. Most web maps use this projection because it keeps angles and shapes right for navigation, not because it shows sizes fairly.
In Globegami you can drag a copy of South Korea anywhere on Earth: it keeps its true size and grows or shrinks on the map as it moves, and you can fold the map back into a globe.
Areas: official totals including inland water (UN Statistics Division via Wikidata). Outlines: Natural Earth. How Globegami works