South Korea is about 3.8 times smaller than Japan.

Japan is approximately 377,915 sq km, while South Korea is approximately 99,720 sq km, making South Korea 26.39% the size of Japan. Meanwhile, the population of Japan is ~124.2 million people (72.4 million fewer people live in South Korea).
This to-scale comparison of Japan vs. South Korea uses the Mercator projection, which distorts the size of regions near the poles. Learn more.

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