How Do You Make Dry Ice at Home? The Checks That Take Almost No Time

Dry ice cannot be made at home, and the gap is equipment rather than effort. Commercial plants release pressurized liquid carbon dioxide into a chamber at atmospheric pressure; the equipment manufacturer ASCO describes "around half of the liquid CO₂" turning into solid snow while the rest discharges as cold gas, after which a press piston forces the snow through an extruder plate into pellets of 1.7 to 16 mm. The NIOSH Pocket Guide lists carbon dioxide's vapor pressure at 56.5 atmospheres and its solid form at −109 °F, which is why the material begins in a pressure vessel and not in a kitchen. For a household, the working route is to buy a few pounds and run four checks that take almost no time: vent the container, keep it out of the passenger cabin, wear insulated gloves, and let the remnants sublime outdoors.

Name the job before choosing the material

Almost nobody wants dry ice for its own sake. The search usually sits on top of one of four jobs: low-hanging fog for a party or a stage, keeping a cooler cold on a long drive, shipping something frozen, or a classroom-style experiment.

Naming the job changes the answer, and often removes dry ice from it. A fog machine produces fog on command. A cooler packed for a weekend needs water ice, which costs a fraction as much and carries no asphyxiation risk. Only the frozen shipment and the genuine cold-science experiment require solid carbon dioxide, and both are better served by buying two or three pounds than by attempting a phase change at home.

Why a kitchen cannot produce solid carbon dioxide

Carbon dioxide has no liquid phase at ordinary pressure. Its triple point sits near 5.1 atmospheres and −56.6 °C, roughly 75 psi; below that pressure the substance moves between gas and solid with nothing in between. Industrial production works around this by starting with liquid CO₂ already under pressure, then dropping that pressure suddenly so the flash-evaporating fraction chills the remainder past freezing.

That is the whole trick, and grocery items cannot reproduce it. Baking soda and vinegar generate carbon dioxide gas at room temperature; nothing in the reaction removes the 109 degrees Fahrenheit of heat separating a household freezer at 0 °F from solid CO₂ at −109 °F. Compressed-gas cylinders can produce snow at the nozzle, but that path puts an untrained person between a pressurized vessel and a cryogenic solid, which is the combination that produces the injuries.

The fire extinguisher demonstration is the wrong answer

The most-shared version of this project discharges a CO₂ fire extinguisher into a cloth bag and collects the snow. It photographs well. It also disables a piece of life-safety equipment for a handful of material that will be gone by morning.

OSHA's portable fire extinguisher standard, 29 CFR 1910.157(c)(4), requires that extinguishers "are maintained in a fully charged and operable condition and kept in their designated places at all times except during use." A CO₂ extinguisher carries no working pressure gauge, because the agent sits as a liquid under its own vapor pressure; charge is confirmed by weighing the cylinder at annual service. A partially emptied unit looks identical on the wall to a full one, and the household that discharged it will not learn otherwise until a fire. Table L-1 of the same standard places carbon dioxide extinguishers on a five-year hydrostatic test cycle performed "by trained persons with suitable testing equipment and facilities." None of that infrastructure travels with a video tutorial.

Buy it, or pick the substitute that matches the job

Walmart, Kroger and Safeway stock dry ice in a branded freezer chest near the front of the store, though availability is store-by-store rather than chain-wide, so calling ahead is the difference between one trip and three. Industrial gas suppliers carry larger quantities, often with a minimum order.

| Option | What it delivers | Main hazard | Where it fails | |---|---|---|---| | Dry ice, purchased | −109 °F cooling; dense fog that hugs the floor in warm water | CO₂ buildup in enclosed spaces; cold injury on contact | Gone within a day or two; needs a vented container and real airflow | | Fog machine | Continuous, controllable fog for as long as it runs | Obscured floor and stairs; slip risk from condensate | Fog rises and disperses unless chilled; cools nothing | | Water ice | Cooling to 32 °F, cheap and available anywhere | Meltwater | No fog; cannot hold frozen goods frozen | | Gel or ice packs | Near-freezing cooling, reusable, airline-friendly | Minimal | No fog; loses frozen-shipment temperatures on long transit |

For a fog effect in a living room, a fog machine is the better instrument and the safer one. For a frozen shipment, dry ice is still correct, and the rules below are what keep it uneventful.

The checks that take almost no time

Keep it out of the passenger cabin

The Cybersecurity and Infrastructure Security Agency's December 2020 primer on dry ice handling states that one pound of dry ice sublimates to produce 8.3 cubic feet of carbon dioxide gas, and instructs readers not to store dry ice "in unventilated rooms, cellars, cars, vans, etc." Cornell's environmental health and safety guidance puts the same figure closer to 8.8 cubic feet per pound; the spread comes from the reference temperature each assumes, and neither changes the conclusion.

Run the arithmetic on a five-pound bag and it releases roughly 41 cubic feet of gas. The EPA classifies a midsize sedan by an interior passenger and cargo volume of 110 to 119 cubic feet under 40 CFR 600.315-08. One grocery-store bag can therefore generate gas amounting to more than a third of the car's interior, and carbon dioxide is 1.53 times as dense as air by NIOSH's own figure, so it settles into the footwells rather than dispersing upward.

In July 2018 the Pierce County Medical Examiner's Office in Washington attributed the death of 77-year-old Hildegard Whiting to carbon dioxide suffocation in a car carrying four coolers of dry ice on the back seat, as reported by CNN and The Washington Post; her daughter-in-law was hospitalized in critical condition. Put the container in the trunk, drive with windows cracked, and keep the trip short.

Store it where gas can leave

The federal packaging rule is unusually blunt. Under 49 CFR 173.217(a), dry ice offered for transport by aircraft or water "must be packed in packagings designed and constructed to permit the release of carbon dioxide gas to prevent a buildup of pressure that could rupture the packagings."

Anyone hunting for a required vent size will not find one. The regulation specifies no minimum vent area, no hole diameter and no square-inch figure; it is a performance standard, and the shipper owns the outcome. In household terms that means a cooler with the lid resting rather than latched, or the vendor's paper bag inside an insulated box. It rules out screw-top jars, sealed plastic bins, zip-closed bags and anything with a gasket. The CISA primer is explicit that gas expansion "could cause an airtight container to explode."

Gloves on, and keep it off the stone

CISA's guidance is to use insulated gloves, noting that prolonged unprotected contact will burn skin. The American Burn Association gives the same instruction and adds the first-aid protocol: treat mild injury with burn ointment and a clean bandage, and seek medical care within 24 hours if blisters develop. Contact injury at −109 °F starts in seconds, not minutes, which is why tongs and gloves are treated as mandatory rather than cautious.

Both bodies also warn against setting dry ice directly on countertops. The primer notes the extreme cold can crack a tiled or solid surface; the burn association extends that to empty glass containers.

Watch the air, not the ice

The NIOSH Pocket Guide sets a recommended exposure limit for carbon dioxide of 5,000 ppm as an eight-hour average, with a short-term limit of 30,000 ppm, and lists 40,000 ppm as immediately dangerous to life or health. Those thresholds describe monitored industrial workplaces with trained staff, and they do not constitute a ventilation plan for a basement party.

Background concentration is one place where authoritative sources plainly disagree. The NIOSH card describes carbon dioxide as a "normal constituent of air (about 300 ppm)," a figure that reflects an older measurement era. NOAA's Global Monitoring Laboratory put the 2024 global average at 422.8 ppm and reported a May 2026 Mauna Loa peak of 432.3 ppm. The ratio survives either version: the eight-hour limit sits roughly twelve times above background, and the IDLH about ninety times.

The Compressed Gas Association's safety bulletin on oxygen-deficient atmospheres gives the other half of the picture. Normal air is 20.9 percent oxygen; below 19.5 percent counts as deficient, and at 8 to 10 percent oxygen, exposure "will bring about unconsciousness without warning and so quickly that the individuals cannot help or protect themselves." The bulletin's instruction for fog work is one line long: never lay down in dry ice fog or any other fog.

Reporting a case in the Journal of Emergency Medicine in 2009, James V. Dunford, MD, of the Department of Emergency Medicine at UC San Diego Medical Center, with co-authors including F. Lee Cantrell, PharmD, of the California Poison Control System, described a 59-year-old man found in cardiac arrest after entering a walk-in freezer that contained dry ice. The paper concluded that the case "illustrates the lethal consequences of improper storage of dry ice and the need to consider toxic environmental exposure as a cause of sudden cardiac arrest." Dunford and colleagues also recorded that first responders and bystanders did not recognize the hazardous environment they had walked into.

Two other published cases mark the edges. Hsieh and colleagues at National Taiwan University Hospital documented carbon dioxide asphyxiation from special-effect dry ice at a 2005 election campaign event. Park and Vanderwal of the University of California, Irvine reported in 2023 a graduate researcher who lost consciousness retrieving dry ice from a deep container holding 180 pounds.

The warning signs CISA lists are worth memorizing before the party rather than during it: panting, dizziness, headache, and fingernails or lips turning blue. The instruction that follows is to leave the area immediately and open windows and doors.

Let the remnants sublime outdoors

Leftover dry ice goes into a vented container in a secure, well-ventilated outdoor spot, and is left alone. Not the sink, not the drain, not the garbage, not a closed bin. CISA also advises against re-entering a closed storage area that has held dry ice until it has aired out completely.

The wait is short. The primer's planning assumption is a loss of 5 to 10 pounds every 24 hours, faster in hot weather, at low air pressure, and when dead-air space surrounds the ice in its container. A few pounds left out on a Saturday evening will generally be gone by Sunday.

Flying with it

Carrying dry ice on a passenger flight is legal and regulated rather than prohibited. Under 49 CFR 173.217(c)(5), quantities not exceeding 2.5 kg (5.5 pounds) per package, used as a refrigerant for the package contents, are excepted from most hazardous materials requirements provided the venting rule in paragraph (a) is met and the package is marked "Carbon dioxide, solid" or "Dry ice," marked with the name of the contents being cooled, and marked with the net weight or an indication that it is 2.5 kg or less.

The TSA states the same limit for carry-on and checked bags and adds the condition travelers routinely miss: airline approval is required, and carriers may set stricter rules than the federal floor.

Frequently asked questions

How long will dry ice last?

CISA's planning assumption is a loss of 5 to 10 pounds every 24 hours in an insulated container. Heat, low air pressure and dead-air space all speed that up, and pellets sublime faster than blocks because they expose more surface. A few pounds bought Saturday morning is typically gone by Sunday.

What can I use if I don't have dry ice?

Match the substitute to the job. A fog machine produces controllable fog indefinitely and creates no asphyxiation risk. Ordinary water ice cools a cooler to 32 °F for a fraction of the cost. Reusable gel packs travel well and are airline-friendly. None of these reach frozen-shipment temperatures, which remains dry ice's genuine advantage.

Is it illegal to carry dry ice?

No. It is regulated as a hazardous material rather than banned. Under 49 CFR 173.217, packages up to 2.5 kg (5.5 pounds) used as a refrigerant are excepted from most requirements when vented and marked. The TSA permits it in carry-on and checked bags, but airline approval is required and carriers may impose stricter limits.

Can I get dry ice from a grocery store?

Frequently, yes. Walmart, Kroger and Safeway stores commonly keep it in a branded freezer chest near the front, and some require the purchase to be requested at the customer service desk. Availability is decided store-by-store rather than chain-wide and thins out near Halloween, so call the specific location first.

Can I make dry ice with baking soda?

No. Baking soda and vinegar release carbon dioxide gas at room temperature, but producing the solid requires reaching −109 °F, and nothing in that reaction removes heat. Industrial plants achieve the temperature by expanding pressurized liquid CO₂ so the evaporating fraction chills the rest. Household chemistry supplies gas, never refrigeration.

Which substitute should I use for fog, cooling, or shipping?

For fog, a fog machine: continuous output, no carbon dioxide accumulation, no gloves needed. For cooling drinks or food over a weekend, water ice or gel packs. For shipping frozen goods, dry ice is still the right material, purchased in a vented container and kept under the 5.5-pound package limit if it is flying.