Japan is about 4.9 times smaller than Sudan.

Sudan is approximately 1,861,484 sq km, while Japan is approximately 377,915 sq km, making Japan 20.3% the size of Sudan. Meanwhile, the population of Sudan is ~51.7 million people (71.7 million more people live in Japan).
Tip: This to-scale comparison of Sudan vs. Japan uses the Mercator projection, which distorts the size of regions near the poles.
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