I did some amateur research to figure out which of the Fallout protagonists (specifically 3, NV, and 4) have a reasonable area of land to constantly traverse. I used Apple Maps to find the straightest possible walking path from a point on either end of the game map, then multiplied the north-south and east-west figures to get an approximate square mileage. Since none of the walking paths were completely straight, these numbers will all be a little higher than actual. BUT the game maps also don’t completely correlate to the real-life locations, so consider these numbers to be estimates.

The Commonwealth: Around 600 square miles. This is honestly pretty manageable, especially if you’re teleporting or helicoptering all over the place. It would be exhausting, but you could theoretically get across the map in a day with time to spare for questing.

The Capital Wasteland: Around 800 square miles. Fairfax is the halfway point; very few locations on the western half of the map actually correspond to anything in real life. The exception is the cavern Little Lamplight is based on, which would make the game map 100 miles long. The map definitely doesn’t extend that far into Virginia.

New Vegas: Kind of hard to calculate at this scale, but we’re looking at a little under 3000 square miles! Through. the Mojave. Desert. The Courier is really going to have to commit to a course of action before traveling, because they won’t be coming back for about a week.

If you’re a fanfic writer, remember that you don’t owe realism to anyone. BUT, if realism is something you care about for your writing, keep these distances in mind!