Montenegro is about 3.5 times smaller than Slovakia.

Slovakia is approximately 49,035 sq km, while Montenegro is approximately 13,812 sq km, making Montenegro 28.17% the size of Slovakia. Meanwhile, the population of Slovakia is ~5.4 million people (4.8 million fewer people live in Montenegro).
Tip: This to-scale comparison of Slovakia vs. Montenegro uses the Mercator projection, which distorts the size of regions near the poles.
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