Oahu is about 1.5 times smaller than Australian Capital Territory.

Australian Capital Territory is approximately 2,358 km² (910 sq mi), while Oahu is approximately 1,545 km² (597 sq mi), making Oahu 65.52% the size of Australian Capital Territory.
Tip: This to-scale comparison of Australian Capital Territory vs. Oahu uses the Mercator projection, which distorts the size of regions near the poles.
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