Should toilet paper hang over or under?

Over wins on the two forms of evidence available. The original 1891 US patent for the perforated toilet paper roll, filed by Seth Wheeler, includes a drawing that clearly depicts the paper feeding over the top of the roll, which is about as close to an authoritative ruling as this dispute allows. And hygiene research on bathroom surfaces supports over as well: hanging under makes users more likely to brush the wall behind the roll while reaching, transferring bacteria to a surface that is rarely cleaned, then back to their hands.

The honest case for under exists but is narrow: it looks tidier against a wall, it is somewhat harder for cats and toddlers to unspool since the roll does not free-wheel as easily, and in a vehicle or boat it swings less. Those are real preferences rather than errors. What makes the debate durable is that it is genuinely trivial and instantly comprehensible, which is the profile of every good household argument, and surveys consistently find a large majority of people prefer over, along with a meaningful minority who report having flipped the roll in someone else's bathroom, which is its own kind of admission.