Heard Island and McDonald Islands is about 88 times smaller than Guinea-Bissau.

Guinea-Bissau is approximately 36,125 sq km, while Heard Island and McDonald Islands is approximately 412 sq km, making Heard Island and McDonald Islands 1.14% the size of Guinea-Bissau.
Tip: This to-scale comparison of Guinea-Bissau vs. Heard Island and McDonald Islands uses the Mercator projection, which distorts the size of regions near the poles.

Compare further: Heard Island and McDonald Islands vs. Guinea-Bissau

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