Are Farts Flammable? Can You Light a Fart on Fire?

The Short Answer

Yes, some farts are flammable — because they can contain hydrogen and methane, two gases that burn readily. But whether any given fart will ignite depends on how much of those gases it contains, which varies a lot from person to person and meal to meal. A fart that's mostly nitrogen and carbon dioxide simply won't catch.

What's Actually in a Fart

A fart is a mixture of gases, roughly in these proportions (though it varies widely):

• Nitrogen — the largest component, not flammable.
• Hydrogen — flammable, produced by gut bacteria fermenting food.
• Carbon dioxide — not flammable.
• Methane — flammable, but only produced by some people.
• Oxygen — small amounts from swallowed air.

The two flammable players are hydrogen and methane. When a fart has enough of them and meets a flame, combustion happens — the same basic reaction that powers a gas hob.

Why Some People's Farts Are More Flammable

Here's the fascinating part: only an estimated one-third to one-half of people produce significant methane, because it depends on whether you host methane-making microbes (called methanogens) in your gut. If you do, your farts carry more flammable gas. Diet matters too — foods that ramp up bacterial fermentation, like beans and other high-fibre gassy foods, increase hydrogen output and make farts more combustible. So "are farts flammable?" genuinely has a different answer for different people.

The Blue Flame

When a fart does ignite, the flame often burns blue. That blue colour is the signature of methane and hydrogen combusting cleanly and at high temperature — the same reason a well-tuned gas stove burns blue rather than yellow. A more orange or yellow flame would suggest other material burning, which is one of several reasons the whole thing is risky.

Why You Should Never Try It

This is firmly in "don't" territory. Lighting a fart means putting an open flame next to one of the most sensitive areas of your body, often near clothing and hair. People have given themselves real burns attempting it. The flame can flash back toward the source, fabric can catch, and there is no version of this that's worth the risk. Enjoy the science, skip the demonstration.

Do not attempt to light a fart. It can cause serious burns. This article is for general interest only.

The Bottom Line

Farts can be flammable thanks to the hydrogen and methane they contain, the famous blue flame is real chemistry, and how flammable your farts are comes down to your personal gut bacteria and diet. It's a genuinely interesting bit of biology — best appreciated from a safe, flame-free distance. For more, dig into our fart facts, find out why farts make noise, or just enjoy the harmless version on the fart soundboard.