Over or Under: We Asked a Physicist to End the World’s Great Toilet Paper Debate


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Over or Under: We Asked a Physicist to End the World’s Great Toilet Paper Debate

What we talk about when we talk about toilet paper orientation.
June 10, 2016, 4:45pm

The other day I was in my bathroom, replacing the toilet paper next to the toilet. I wasn't really paying attention to what I was doing and ended up putting it on "backward," with the "tear" of the toilet paper facing the wall, rather than facing outward. I didn't think anything of it. Who cares—there's not actually a "right" way to put toilet paper on the thing, is there? It turns out that many people do think there is a right way to put the toilet paper on the thing, and one of those people is my girlfriend.

"The toilet paper goes the other way!" she told me after she saw what I'd done. When I asked her why she felt like that, she said, "I don't know, that's just not the way people do it."


The question of which way toilet paper "ought" to hang is one of those topics that gets batted around the internet at a low-level hum. The debate has its own entry on knowyourmeme, as well as a shockingly long Wikipedia article devoted to the topic. Every couple of years, a website or two will proclaim to have resolved the issue due to the discovery of some heretofore undiscussed piece of evidence. Last year, the Huffington Post trotted out the original patent for toilet paper to point out that its inventor, a man named Seth Wheeler, had originally intended it to go on the roll with the tear facing outward.

For what it's worth, precedent truly does seem to point to the "over" position on the roll. There is the evidence offered by the aforementioned patent, as well as a recent Cottonelle ad campaign concerning the subject, which incorporated a survey proclaiming that 74 percent of Americans preferred the fold of their toilet paper facing them. If we're judging by how true Americans hang their toilet paper, we can always ask Kid Rock, the most American American ever to come out of America. In Rock's music video "You Never Met a Motherfucker Quite Like Me," the rappin' redneck pride of Detroit wipes his ass with a roll of toilet paper emblazoned with the word "Radiohead," which was hung—you guessed it—facing outward.

But is there a scientific reason why one direction is favored over the other? To answer this question, I turned to the theoretical physicist Brian Wecht, who has conducted research at Harvard as well as MIT, and lectured at Queen Mary University of London before pursuing a career as a full-time YouTuber as half of the musical comedy duo Ninja Sex Party. He explained that, no matter which way the paper is facing, the same physical principle is at play. His official take? "It doesn't matter."


"When something spins," he explained, "it creates rotational kinetic energy: the energy of motion." The force required to make it rotate is called torque, which in this case is created by your hand spinning the roll or pulling down on the paper. He continued, "Whether you hang toilet paper facing against the wall or facing forward, the rotational kinetic energy you impart on the roll is the same, and it requires the same amount of torque. They're mirror images of each other, which means the amount of energy you have to expend is the same."

For a second opinion, I checked in with Nicholas DiBella, a philosophy PhD candidate at Stanford who got his degree in physics from MIT. We spoke over the phone after he'd just successfully defended his thesis, which uses set theory and probability to argue against the traditional metaphysical convention that the world is simple and is in fact extremely complex. While he agreed that Wecht was right in saying that there was a physical symmetry no matter which way you face toilet paper, he added, "There is an asymmetry that comes in when you factor in human ability.

"Normally when people sit on the toilet, they want to apply minimal effort," he said. "Which means people yank at the paper," rather than just spinning the roll. "They tear tangentially to the roll—left to right. When the toilet paper is at the front, it gives people more space within which to rotate their arm."


Debates such as this one are ultimately asinine (and perhaps inevitable in domestic partnerships such as my own), but they reveal a greater truth concerning the way we talk about the things we do in the bathroom, said Professor Harvey Molotch of NYU. Molotch is an urban sociologist and expert in the field of industrial design who co-edited a book of academic writing on bathrooms that was simply titled Toilet. "I've lived a long life, and I've done many, many interviews about toilets," said Molotch, who is 76. "But nobody has ever asked me about this before."

According to Molotch, there is a reason people have deeply personal, often idiosyncratic beliefs about things that go on in the bathroom. People who design bathrooms, he told me, often refer to toilets and their related paraphernalia as "taboo products." He explained, "These things can't be discussed easily—even with clients, much less average people." This "forbidden discourse," as Molotch put it, is one of the reasons we still rely on toilet paper at all, when there are a number of arguably superior alternatives on the market. Products like baby wipes, moist towelettes, bidets, and sustainable cloth rags "have had a hard time finding a niche because nobody wants to describe what they're for," said Molotch. "Toilet paper in general is advertised only vaguely. You can never show the location where it's used, which is your ass."

When I asked Molotch to analyze the outward-facing toilet paper tradition, he ventured that it might have its roots in the hospitality industry. "Hotels like putting the paper tear-forward, so they can fold it, or even do little origami tricks to it, to show they've cleaned," he said. "It's a little art exhibition to display this idea of, 'Don't worry, the shithole is approachable.'"

And while Molotch understands precedent, the idea of toilet paper facing outward personally rankles him. "I'm efficiency-oriented," he said. "And having the toilet paper toward the back saves me about two inches." This method, he argued, orients the paper "adjacent to the wall rather than in the room."

Regardless of his personal preference, Molotch innately understood the issue's universal appeal. "It's a fun question," he said. "It's got a glimmer of mischief to it—it's a way of taking something nobody ever talks about and making it approachable."

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