What gas is in chip bags?
The “air” in a bag of chips (crisps, in the UK) is mostly nitrogen. Snack makers flush each bag with an inert gas, usually nitrogen, to remove oxygen just before it is sealed. Sebastian Emig, director general of the European Snacks Association, explains that this is done “to preserve the freshness of the product” [2]. The technique is a form of modified atmosphere packaging.
Nitrogen is a good choice because it is cheap, it does not react with food, and it already makes up about 78% of the air we breathe [5]. It has no taste or smell and is completely safe to eat around.
Why are chip bags filled with nitrogen?
There are two reasons, and both are about getting the chips to you in good condition.
- Freshness. Oxygen reacts with the oils in chips, turning them rancid, and moisture in normal air makes them go soft and stale. Replacing the air with dry nitrogen slows both, so the chips stay crisp on the shelf [1][2].
- Protection. The inflated bag works like a pillow. Emig describes the gas as cushioning the product “from damage whilst being transported, stored or sold” [2]. A bag with no gas would arrive full of crumbs.
There is also a practical reason the bag is bigger than the chips. Filling machines drop a measured weight of chips into each bag, and loose chips settle and break down during shipping. Some headspace is unavoidable [4].
How much of a chip bag is air?
Kitchen Cabinet Kings, a US retailer, tested 14 popular brands using water displacement: they sank each sealed bag in water and marked the level, then vacuum-sealed the chips alone and measured again. Each brand was tested twice and the results averaged [1]. As their chart above shows, the average bag was 43% gas [1]:
| Brand | Share of bag that is air |
|---|---|
| Cheetos | 59% |
| Ruffles | 50% |
| Stacy’s Pita Chips | 50% |
| TERRA | 49% |
| Doritos | 48% |
| Kettle Brand | 47% |
| Cape Cod | 46% |
| Popchips | 45% |
| Lay’s | 41% |
| Sun Chips | 41% |
| Lay’s Baked | 39% |
| Tostitos Scoops | 34% |
| Pringles | 28% |
| Fritos | 19% |
Premium and “healthier” brands were no better than the classics: TERRA, Kettle Brand and Popchips all came in at 45% to 49% [1]. Shape makes the biggest difference. Light, irregular snacks like Cheetos and Ruffles leave lots of gaps, while small, dense Fritos seem to pack more tightly, and Pringles stacked in a tube use their container more efficiently than loose chips [1][3].
These figures describe the bags tested, one size per brand. Air share varies between bag sizes and individual bags, and the study does not say exactly when it was carried out; the earliest write-up we found dates from 2018 [2]. It compares its result with a 2015 experiment by the artist Henry Hargreaves that found about 70% air, though the two used different brands and methods [1].
Is it legal to sell half-empty bags?
Yes, within limits. In the US, the Food and Drug Administration’s rule on misleading containers defines “slack-fill” as the difference between a container’s capacity and the volume of product inside. Empty space is only treated as misleading if it is “nonfunctional”. Protecting the contents, the needs of packing machines and unavoidable settling during shipping all count as legitimate reasons [4]. The weight of the contents must be printed on the pack, so you can compare value by weight rather than by bag size [2].
That is the useful takeaway for shoppers: judge a bag of chips by the net weight and price per 100 g, not by how big it looks on the shelf.
Why do chip bags puff up on planes and in the mountains?
The gas sealed in the bag stays at the pressure it was packed at, usually close to sea level. As you go higher, the air pressure outside drops, so the gas inside expands and the bag swells, sometimes until it bursts. This is Boyle’s law: at a constant temperature, the volume of a gas rises as its pressure falls [6]. The same thing happens to a sealed water bottle on a flight. It is harmless to the chips, and the flexible, partly filled bag copes with it better than a rigid, tightly packed one would.
Questions about air in chip bags
What is the air in chip bags called?
It is nitrogen gas, added in a process called nitrogen flushing or modified atmosphere packaging [2].
Is the nitrogen in chip bags safe?
Yes. Nitrogen is inert and already makes up most of the air we breathe [5].
Why are chip bags half air?
The gas keeps the chips fresh by excluding oxygen and stops them breaking in transit, and some space is needed for filling and settling [1][2][4].
Which chips have the most air?
In the Kitchen Cabinet Kings test, Cheetos, at 59% air. Fritos had the least, at 19% [1].
How much air is in a bag of chips on average?
43% across the 14 brands tested [1].
Sources
- Kitchen Cabinet Kings, How Much Air is in Your Bag of Chips?, the original study and chart.
- Keilah Keiser, How much air is in your bag of chips?, Bakery and Snacks, 20 June 2018.
- Sporcle, Why Are Chip Bags Full of Air?, 10 September 2021.
- US Code of Federal Regulations, 21 CFR 100.100, Misleading containers.
- Wikipedia, Atmosphere of Earth.
- Wikipedia, Boyle’s law.
Last reviewed 2 November 2026
