Japan is about 3.9 times smaller than Alaska.

Alaska is approximately 1,481,348 sq km, while Japan is approximately 377,915 sq km, making Japan 25.51% the size of Alaska. Meanwhile, the population of Alaska is ~710,231 people (123.5 million more people live in Japan).
Tip: This to-scale comparison of Alaska vs. Japan uses the Mercator projection, which distorts the size of regions near the poles.
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