Australia dwarfs North America: about 7,706,009 km² km² against 24,710,000 km² km². At true size Australia is about 3.2× larger — the whole of North America fits into Australia roughly 3 times.
The old Mercator map treated both about equally (1.2× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Australia fits 3× into North America.