Mongolia dwarfs United States: about 1,560,428 km² km² against 9,439,424 km² km². At true size Mongolia is about 6× larger — the whole of United States fits into Mongolia roughly 6 times.
Mongolia sits in Asia, 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 6×.
The old Mercator map treated both about equally (2.2× vs 2× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Mongolia fits 6× into United States.