Closer than most people guess: Algeria (2,322,788 km² km²) is only about 24%% larger than Indonesia (1,872,242 km² km²).
Algeria sits in Africa, Indonesia in Asia. On the old Mercator map the latitude gap distorted how large each felt beside the other; at true size the answer is simply 1.2×.
The old map muddied it further: Mercator inflates Algeria about 1.3× and Indonesia about 1×, so on a Mercator-style map this pair appears 1.6× apart instead of the true 1.2×.
Indonesia fits 1× into Algeria.