Though it’s often the butt of jokes and a source of embarrassment, farting is an important and completely normal bodily function, allowing the body to release intestinal gases produced during digestion.
But if you’re prone to flatulence or are just going through a distressingly gassy period, you may wonder: How much farting is typical?
The medical literature offers an amount. But a recent study suggests the number of times a person farts a day, on average, is about twice as much as previously thought.
The investigators behind the study say it’s important to have an accurate “flatulence baseline” in order to pursue bigger questions about problems related to diet, microbiome activity, and gastrointestinal symptoms.
“You can’t define what’s abnormal until you know what normal looks like,” says Brantley Hall, PhD, an assistant professor of cell biology and molecular genetics at the University of Maryland in College Park, who’s leading the new research.
How Many Times Does a Person Fart Per Day?
The study, published in December, found that healthy adults passed gas 32 times a day on average — far more often than the 14 times per day that’s typically reported in medical literature.
But there was “enormous individual variation,” ranging from 4 to 59 daily farts, Dr. Hall says.
He and his team arrived at these numbers through the use of so-called Smart Underwear — a tiny device they designed that can snap onto any undergarment. The apparatus uses sensors to detect hydrogen and other gases in flatus (or farts) produced throughout the day and night.
“Earlier estimates were lower because they relied on self-reporting, which is unreliable,” says Hall. That research involved asking people to “count their own farts, which doesn’t work well,” or using “extremely invasive techniques” like rectal tubes in a clinical setting.
He and his team tested the Smart Underwear in 38 healthy adults who had consumed prebiotic fiber in a controlled dietary challenge, Hall says.
“For the first time, we can measure flatus production objectively and continuously in people going about their normal lives,” Hall says.
What Causes Farting?
People swallow air throughout the day, especially when they eat quickly, chew gum, drink carbonated beverages, or talk while eating, explains Supriya Rao, MD, a gastroenterologist who was not involved in the study.
“That air travels through your digestive tract, and the portion that is not burped out eventually moves through your intestines and is released as gas,” Dr. Rao says.
Foods contribute to gas, too, especially those high in fiber and certain sugars like lactose or fructose and fermentable carbs, which increase fermentation, she notes. “The by-products are gases like hydrogen, methane, and carbon dioxide. Our gut bacteria ferment carbohydrates that are not fully digested in the small intestine.”
How much you fart per day depends on your gut microbiome, she adds. Some people produce more gas than others. You should know what’s normal for you so you can recognize when something feels off.
What Tracking Flatulence Could Tell Us About Gut Health
The amount and type of gas a person produces reflects how their gut bacteria ferment food, Rao says. For instance, higher methane production may suggest slower intestinal transit and constipation, while more hydrogen production can offer clues about lactose intolerance and small intestinal bacterial overgrowth (SIBO).
“Because hydrogen in flatus is produced exclusively by gut microbes, tracking it gives us a direct, continuous readout of when and how actively your gut microbiome is fermenting the food you eat,” Hall says.
“So tracking gas production gives us a window into what the microbiome is actually doing, not just which microbes are present,” Hall says.
It’s important to note that very smelly gas is usually just a reflection of what you ate and how your gut bacteria are fermenting it; it’s rarely a sign of something serious, Rao says.
But if you have excessive gas alongside chronic diarrhea, severe bloating, or constipation, talk to your doctor, she emphasizes.
Research on Flatulence Is Ongoing
The findings of the first study are limited by its small number of volunteers. To establish a true “flatulence baseline,” Hall and his team have launched the Human Flatus Atlas, an ongoing project using the Smart Underwear to measure flatulence patterns among hundreds of participants.
Hall says the team anticipated recruiting about 800 participants, but 3,000 signed up, so the researchers paused enrollment.
The project is especially interested in “zen digesters,” or those who eat high-fiber diets but produce little gas, and “hydrogen hyperproducers,” who are especially gassy.
“Those two groups are the key to unlocking why some microbiomes handle fiber efficiently while others don’t,” Hall says. “If we can figure out what’s different about those microbiomes, it advances our understanding of how the gut microbiome works in ways that go far beyond flatulence.”
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