Closer than most people guess: Brazil (8,499,400 km² km²) is only about 11%% larger than United States (9,439,424 km² km²).
Brazil sits in South America, United States in North America. On the old Mercator map the latitude gap distorted how large each felt beside the other; at true size the answer is simply 1.1×.
The old map muddied it further: Mercator inflates Brazil about 1× and United States about 2×, so on a Mercator-style map this pair appears 2.1× apart instead of the true 1.1×.
Brazil fits 1× into United States.