How many Olympic medals did Michael Phelps win?

How to get close to this number

Multiply games by events by medals. Swimming offers an unusual number of events to a single athlete — different strokes, different distances, and relays — so a dominant swimmer can enter seven or eight events per Games. Five Games at that rate, with a very high win rate, produces a total in the high twenties.

The sport is the whole explanation, and it is worth being explicit about it. A sprinter has two or three chances per Games and a marathon runner one; a swimmer has many, because the same physical capability is tested across a grid of strokes and distances. Medal totals measure opportunity as much as dominance, and swimming offers more opportunity than almost any other sport.

The comparison in the explanation is the one that lands: more gold medals than all but about sixty entire countries have won in Olympic history. Comparing an individual to nations is usually rhetorical excess; here it is arithmetically accurate, and it is the clearest possible statement of how concentrated Olympic success can be.