South Australia is about 1.2 times bigger than New South Wales.

New South Wales is approximately 801,150 km² (309,326 sq mi), while South Australia is approximately 984,321 km² (380,048 sq mi), making South Australia 23% larger than New South Wales.
Tip: This to-scale comparison of New South Wales vs. South Australia uses the Mercator projection, which distorts the size of regions near the poles.
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