Algeria dwarfs Australia: about 2,322,788 km² km² against 7,706,009 km² km². At true size Algeria is about 3.3× larger — the whole of Australia fits into Algeria roughly 3 times.
Algeria sits in Africa, Australia in Oceania. On the old Mercator map the latitude gap distorted how large each felt beside the other; at true size the answer is simply 3.3×.
The old Mercator map treated both about equally (1.3× vs 1.2× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Algeria fits 3× into Australia.