The chore that costs less in forgone work
Comparative advantage is about opportunity cost: the value of the next-best thing someone gives up when they take on a task. It can point to a different person than “who does it fastest.”
Suppose Alex can clean in 30 minutes or cook dinner in 60. Blair needs 40 minutes to clean or 100 to cook. Alex is faster at both chores. But cleaning costs Alex half a dinner’s worth of time; for Blair, it costs only two-fifths of a dinner. Blair gives up less by cleaning, so Blair has the comparative advantage there. Alex can cook.
Together, that assignment takes 100 minutes of work. If Alex cleans and Blair cooks, it takes 130. The gain comes not from either roommate becoming faster, but from each doing the chore that uses less of their time relative to their other option.
Efficiency still needs an agreement
This calculation works best when chores are reasonably comparable and people can actually trade responsibilities. It does not decide whether the arrangement feels fair: one chore may be more unpleasant, schedules may differ, or the person doing less time-consuming work may still carry a heavier burden in other ways.
Roommates can use comparative advantage to find an efficient starting point, then balance the workload through rotation or another agreed arrangement. The practical lesson is that dividing chores by speed alone can waste time—even when the fastest person seems like the obvious choice.
