Chad dwarfs Oceania: about 1,270,927 km² km² against 8,600,000 km² km². At true size Chad is about 6.8× larger — the whole of Oceania fits into Chad roughly 6 times.
The old Mercator map treated both about equally (1.1× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Chad fits 6× into Oceania.