Farting is normal, but how much is normal?

Passing gas, also known as flatulence (and roughly nine hundred less formal names), is something most people treat as either hilarious or mortifying. But strip away the giggles and the embarrassment, and you find an essential bodily function. Without it, gas would pile up inside your stomach and intestines, stretching them painfully and leaving you bloated and miserable. Farting is your digestive system politely letting off pressure.

Here is the funny thing, though. Despite being one of the most universal human experiences, science never had a solid answer to a basic question: how many times per day does a healthy person actually pass gas? A new study, published in JAMA Network Open, finally set out to count.

Where does all that gas come from?

The gas you eventually release is a blend from two very different sources.

1. Swallowed air (the technical term is aerophagia). Every time you eat, drink, chew gum, or even talk, you swallow tiny amounts of air. This air is mostly nitrogen and oxygen, the same stuff floating around the atmosphere. It is odorless and totally harmless. Some of it comes back up as a burp, and the rest takes the scenic route through your digestive tract before exiting as flatulence. So a good chunk of any given fart is just the air you accidentally gulped down at lunch.

2. Gas made by gut bacteria (bacterial fermentation). This is where things get interesting, and where the smell comes from. Your large intestine houses trillions of bacteria that help break down food, especially complex carbohydrates like dietary fiber that your own enzymes cannot handle.

When those bacteria chew through this food, they pump out gases as byproducts through a process called fermentation. It is the same basic process yeast uses to make bread rise, except the venue is your colon. The main gases produced include:

• Hydrogen (H₂): Made when bacteria ferment undigested carbohydrates.

• Methane (CH₄): Made by a specialized group of microorganisms called methanogens. (Fun technicality: methanogens are not bacteria at all. They belong to a separate domain of life called archaea.) Not everyone hosts large populations of methanogens, which is why some people produce far more methane than others.

• Carbon dioxide (CO₂): Made through various bacterial reactions.

• Hydrogen sulfide (H₂S) and other sulfur compounds: Produced in small amounts when bacteria break down sulfur containing amino acids (the building blocks of proteins) found in foods like eggs, meat, broccoli, and beans.

Here's the kicker on that last one. Those sulfur compounds make up less than 1% of the total gas volume, yet they are responsible for the entire notorious smell. The human nose is freakishly sensitive to hydrogen sulfide, able to detect it at concentrations as low as a few parts per billion. So a fart can be 99% odorless gas and still clear a room thanks to a sliver of sulfur.

High fiber foods like beans, lentils, whole grains, and certain vegetables tend to produce more gas. That's because they contain complex sugars (with names like raffinose and stachyose) that human enzymes cannot digest. These sugars sail intact into the large intestine, where the bacteria greet them like a buffet and ferment away. The old "beans, beans, the musical fruit" rhyme is, scientifically speaking, accurate.

What the study found

Researchers from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia built a mobile app with an unbeatable name: Chart Your Fart, available on both Android and iOS. More than 6,400 Australians aged 14 and older, all free from any recent major dietary changes, used the app to log every single instance of passing gas in real time for at least three days.

Here are the headline results:

• The average person passed gas about 5 times per day.

• Nearly 80% of participants fell within a range of 2 to 7 times daily.

• Men averaged 5.2 times per day, compared with 4.8 times for women. This gap may come down to differences in diet, gut bacteria, or hormonal effects on gut motility (how fast food travels through the digestive tract).

• The youngest group (ages 14 to 25) reported passing gas less often than every other age group. This could reflect different diets, different gut bacteria, or, let's be honest, possibly just teenagers being less willing to log it in an app.

• Flatulence followed a clear daily rhythm. Gas passing stayed low through the middle of the day, then started climbing after 6 p.m., peaking between 6 p.m. and 10 p.m. That timing lines up with when people usually eat their biggest, highest calorie, highest fiber meals. After a large dinner, more undigested material reaches the large intestine, handing the gut bacteria extra fuel to ferment. More fuel, more gas. Your evening toots are basically a status report on dinner.

Why anyone bothered to study this

This may be one of the first studies to describe real time flatulence habits in a large, general population of healthy people. Previous research usually involved small groups or focused only on people with digestive disorders like irritable bowel syndrome (IBS), which can cause excessive gas, bloating, and belly pain. Useful, but not a great picture of what "normal" looks like for everyone else.

And knowing what's normal genuinely matters, because both extremes can signal trouble.

Too much gas can be uncomfortable and may point to food intolerances. One common example is lactose intolerance, where the body lacks enough of an enzyme called lactase to digest the sugar in milk, leaving it for the bacteria to ferment (and produce gas). Excess gas can also signal bacterial overgrowth in the small intestine (a condition called SIBO, short for small intestinal bacterial overgrowth) or other digestive issues.

Too little gas is actually the scarier direction. A sudden inability to pass gas, especially when it comes with stomach pain and bloating, can be a warning sign of a bowel obstruction (a blockage in the intestine) or another serious gut problem that needs medical attention fast. A bowel obstruction stops gas and stool from moving through, causing a dangerous buildup of pressure. In short, the body's plumbing has backed up, and that is a genuine emergency.

🚨 Sudden inability to pass gas, plus severe abdominal pain and bloating, is a possible bowel obstruction — go to the ER, don't wait it out.

Untreated bowel obstruction can lead to intestinal rupture, sepsis, and death within hours. The warning signs to take seriously:

• Sudden, severe abdominal pain that comes in waves or is constant

• Inability to pass gas or stool for an extended period

• Severe bloating with a hard, distended abdomen

• Vomiting, especially if it smells fecal

• No bowel sounds (silent belly) or unusually high-pitched sounds

Higher risk: anyone with prior abdominal surgery (adhesions are the #1 cause), hernias, inflammatory bowel disease, or known abdominal tumors. Get to the emergency department — this is a CT-scan-and-surgical-consult situation, not a wait-and-see one. If you can't reach the ER, call 911. Antinausea meds, laxatives, and home remedies don't fix obstruction; they can make it worse.

By pinning down a baseline for normal, this research gives doctors and patients a real reference point. It can make conversations about digestive symptoms less awkward and more productive, and it might even help society loosen up and treat flatulence as the normal, healthy function it actually is. (A noble goal, though we suspect middle schoolers will keep laughing regardless.)

The bottom line: Passing gas about 2 to 7 times a day is perfectly normal for most people, with an average around 5 times daily, and you can expect a peak in the evening after a big meal. Most of a fart is harmless swallowed air, while a tiny dose of sulfur compounds supplies the smell. The thing to watch for is a big change from your usual pattern, either much more or much less than normal, especially alongside pain or bloating. If that happens, it is worth mentioning to a doctor. Otherwise, rest easy. Your gas output is just your gut bacteria filing their daily report.

This article is for general education and isn't medical advice. The 2-to-7-times-daily range is a healthy population average, not a strict rule — individuals vary, and what's normal for you matters more than the average. The red flags that warrant evaluation: a big and persistent change from your normal pattern, blood in stool, unintentional weight loss, persistent abdominal pain, or any of the bowel obstruction warning signs above. If gas is socially distressing or significantly interfering with your life, a gastroenterologist can help — there are real diagnostic and treatment options for SIBO, lactose intolerance, food sensitivities, and other underlying causes.