Soda cans explode in the refrigerator because the liquid inside freezes, and water expands as it turns to ice. Since a sealed aluminum can has almost no room to accommodate that expansion, internal pressure spikes until the thin metal walls give way. The culprit is almost always a freezer compartment, a thermostat set too low, or a cold zone near the back wall of the fridge where temperatures dip below freezing.
How Freezing Tears a Can Apart
Water is unusual among common liquids in that it takes up more space as a solid than as a liquid. When water molecules lock into ice crystals, the resulting structure is roughly nine percent larger by volume than the liquid it came from. In a sealed soda can, that expansion has nowhere to go. The can’s walls and lid are already under pressure from dissolved carbon dioxide, so adding the outward push of expanding ice creates a force the container was never designed to handle.
The carbon dioxide itself makes things worse. As the liquid portion of the soda shrinks and ice crystals form, COâ‚‚ that was dissolved in the liquid gets forced out of solution. That gas needs space, and with the can already swelling from ice expansion, the combined pressure from expanding ice and escaping gas overwhelms the aluminum. The result is usually a split along the sidewall or a blown-out lid, followed by a sticky mess coating every surface in the freezer.
Aluminum Cans Are Thinner Than You Think
A modern soda can is an impressive feat of lightweight engineering, but that same efficiency is exactly why it fails so dramatically when frozen. The sidewall of a 12-ounce aluminum can is less than four thousandths of an inch thick. That is thinner than a sheet of standard printer paper. Can manufacturers have spent decades shaving material to reduce costs and weight, and the trade-off is a container that operates surprisingly close to its structural limits even under normal conditions.
At room temperature, a carbonated beverage typically exerts about 50 to 60 psi of internal pressure on the can. The resulting stress in the sidewall is already around 45 percent of the aluminum alloy’s yield stress, which is the point at which the metal starts to permanently deform.1Engineering Fracture Mechanics. A pressure vessel fracture mechanics study of the aluminum beverage can Under severe conditions like heat or, at the other extreme, internal ice expansion, pressure inside the can can climb to 90 psi or beyond, pushing the wall stress well past what the aluminum can tolerate. A can does not need to reach textbook bursting pressure to fail. Any small defect, dent, or scratch on the sidewall can become the starting point for a crack once the stress climbs high enough.
Temperature also affects the metal itself. Research on the aluminum alloys used for can lids has shown that storage conditions change the material’s mechanical strength over time. Cans stored in warm conditions for a month showed about a 10 percent decrease in strength compared to cans kept in cooler environments.2PubMed Central. The Impact of Temperature Conditions on the Manufacturing Process and Mechanical Behavior of Beverage Can Ends during Operation While that study focused on warm-climate aging, the broader point matters: a can’s ability to resist pressure is not fixed. Its history of temperature exposure plays a role, and a can that has been sitting in a hot garage before being tossed in the freezer may be slightly weaker than one that was refrigerated from the start.
Why Your Fridge Can Act Like a Freezer
Most people who discover an exploded soda did not deliberately put it in the freezer. They put it in the refrigerator and forgot about it, or they placed it in a spot they assumed was safe. Household refrigerators are not uniformly cold. The back wall, especially near the cooling element or evaporator coils, is often several degrees colder than the middle shelves. Cans pushed to the back of the fridge or placed directly against the rear panel can sit in a microclimate that drops below 32°F (0°C) even when the rest of the compartment is a comfortable 37°F.
Thermostat accuracy is another common issue. Older refrigerators or units with failing temperature sensors can cycle into temperatures well below their set point. If you have ever found lettuce frozen in the back of the crisper drawer, your fridge has the same cold-spot problem that can freeze a soda can. Overcrowding makes this worse, because tightly packed items block air circulation, allowing cold air to pool in certain areas rather than distributing evenly.
The freezer compartment itself is the most obvious hazard. People routinely put a warm can in the freezer to chill it quickly and then forget about it. A 12-ounce can of soda in a standard home freezer (set to around 0°F or −18°C) will typically begin to freeze within two to three hours, depending on the initial temperature and how full the freezer is. Once ice formation starts, the can has limited time before something gives.
Diet Soda Freezes Faster Than Regular
Not all sodas freeze at the same temperature, and this difference trips people up. Regular soda contains a substantial amount of dissolved sugar, often in the form of high-fructose corn syrup or sucrose. Dissolved solutes lower the freezing point of a solution, a basic physical property that keeps ocean water liquid at temperatures below the freezing point of pure water. Fructose, in particular, is recognized for its freezing-point depression properties in food and beverage applications.3The American Journal of Clinical Nutrition. Manufacturing, composition, and applications of fructose
A typical can of regular cola contains about 39 grams of sugar. That amount of dissolved sugar pushes the freezing point down to roughly 28°F (−2°C) or slightly lower, depending on the exact formulation. Diet soda, on the other hand, replaces sugar with artificial sweeteners that are effective in tiny quantities, contributing almost nothing to freezing-point depression. A can of diet soda freezes at a temperature very close to 32°F, just like plain water. In practical terms, this means a diet soda left in the back of a fridge with cold spots is more likely to freeze and explode than its sugary counterpart sitting right next to it.
This is one reason you might find a burst can of diet cola in your fridge while the regular cola beside it is perfectly fine. The sugar difference, not the carbonation, is what made one can more vulnerable. If you are chilling cans quickly in a freezer, diet versions need to come out sooner.
Plastic Bottles Handle Freezing Differently
If you have ever frozen a plastic bottle of soda, you know the outcome is different from a can. The bottle swells, sometimes dramatically, but it usually does not burst. PET (polyethylene terephthalate) plastic, the material used for most soda bottles, is flexible enough to deform outward as ice expands inside. The bottle balloons out, the cap may bulge, and the bottle becomes rock-hard, but the seal often holds. That deformability gives plastic a significant advantage in surviving freezing.
Aluminum cans lack that flexibility. Once the internal pressure exceeds the wall’s capacity, the metal does not stretch gracefully. It cracks, and the contents escape. Glass bottles split the difference: they are rigid like cans but thicker-walled. Glass can sometimes survive mild freezing if there is enough headspace at the top of the bottle, but a fully frozen glass bottle of soda will crack or shatter, creating a more dangerous mess than a burst aluminum can because of the glass shards.
PET bottles dominate the soda market alongside aluminum cans in the United States, with cans accounting for roughly 60 percent of carbonated soft drink packaging and PET bottles about 17 percent.4Environmental Science & Technology. Replacing Plastics with Alternatives Is Worse for Greenhouse Gas Emissions in Most Cases Glass bottles hold a tiny fraction of the market. So the most common container people are likely to accidentally freeze is also the one least able to survive it.
What Happens After Thawing
A can that froze but did not burst is not necessarily safe to open casually. When soda freezes, COâ‚‚ that was dissolved in the liquid gets concentrated in the remaining unfrozen portion and partly released as gas trapped in pockets within the ice. As the can thaws, that gas wants back into solution, but the equilibrium has been disrupted. Opening a thawed can often produces vigorous fizzing or outright gushing as the COâ‚‚ escapes all at once.
Research on gushing in canned beverages has shown that tiny bubbles already present in the liquid act as starting points for rapid gas release. When those bubbles are disturbed or modified, the subsequent fizzing behavior changes significantly.5Journal of Colloid and Interface Science. Gushing in canned beer: the effect of ultrasonic vibration Freezing and thawing is one of the most aggressive ways to disturb those tiny bubble sites. The ice crystals that formed and melted leave behind a liquid full of disrupted nucleation points, primed to release gas the moment the pressure seal is broken by popping the tab. If you thaw a can that survived intact, open it slowly over a sink.
The soda will also taste flat or off. Freezing and thawing cause carbonation loss because the gas that escaped from solution during freezing does not fully redissolve. You are left with a drink that is less fizzy and may have a slightly altered flavor, since carbonation contributes a mild acidity that affects how sweetness registers on your tongue.
Preventing the Mess
The simplest prevention is a timer. If you put a can in the freezer for a quick chill, set an alarm on your phone for 30 to 45 minutes. That is enough time to get the drink cold without approaching freezing temperatures inside the can. Wrapping the can in a wet paper towel before putting it in the freezer speeds up cooling through evaporation, so you can reduce the time to around 15 to 20 minutes.
For cans stored in the refrigerator long-term, keep them away from the back wall and out of the lowest shelves where cold air tends to settle. If your fridge has a known cold spot, an inexpensive refrigerator thermometer placed in different locations over a day or two will reveal where temperatures dip below safe levels. The ideal fridge temperature for food safety is around 37°F (3°C), which gives a comfortable margin above the freezing point of diet soda and an even wider buffer for regular soda.
If you have already found the aftermath of an explosion, unplug the freezer or fridge section before cleaning. The sticky residue from soda is much easier to remove with warm water before it dries and hardens. If the can ruptured violently, check for sharp aluminum edges. A burst can sometimes peels open in jagged strips that can easily cut your fingers during cleanup.
Cans Left in a Hot Car and the Opposite Problem
Freezing is not the only way a soda can fails under temperature stress. The opposite extreme, heat, can cause the same outcome through a different mechanism. On a hot day, the temperature inside a parked car can climb above 140°F (60°C). At those temperatures, the COâ‚‚ dissolved in the soda becomes much less soluble, and more of it escapes into the headspace as gas. Internal pressure can climb to 90 psi or higher, which puts the sidewall stress dangerously close to the aluminum’s breaking point.1Engineering Fracture Mechanics. A pressure vessel fracture mechanics study of the aluminum beverage can
The failure mode in heat is a pure pressure rupture rather than an ice expansion event. The can does not swell the same way, because the liquid inside is not changing phase. Instead, the gas pressure simply exceeds the wall’s tolerance and the can pops open, often at the weakest point like a seam or near a pre-existing dent. Cans that have been heat-aged are particularly susceptible, since prolonged warmth weakens the aluminum alloy over time.2PubMed Central. The Impact of Temperature Conditions on the Manufacturing Process and Mechanical Behavior of Beverage Can Ends during Operation A can that spent weeks in a warm warehouse before reaching your hands may already be operating closer to its limits than a freshly manufactured one.
The practical takeaway is that soda cans live in a surprisingly narrow temperature comfort zone. Below about 28°F, freezing threatens them. Above about 120°F, heat and gas pressure do the same job. The standard range of a functioning refrigerator or a room-temperature pantry keeps the can well within its design window, and that is where your soda belongs.
Why the Can Is Designed This Way
You might wonder why manufacturers build a container so vulnerable to common temperature swings. The answer is economics and materials efficiency. Aluminum is expensive, and the beverage industry produces hundreds of billions of cans per year worldwide. Shaving even a fraction of a gram from each can translates to enormous savings in raw material costs. The industry has progressively reduced the amount of aluminum in each container for decades, resulting in the paper-thin sidewall that exists today.1Engineering Fracture Mechanics. A pressure vessel fracture mechanics study of the aluminum beverage can
This is a calculated trade-off. A thicker-walled can would survive freezing and extreme heat more reliably, but it would cost more, weigh more, and generate higher carbon emissions during production. Aluminum cans already produce about twice the greenhouse gas emissions of an equivalent PET plastic bottle.4Environmental Science & Technology. Replacing Plastics with Alternatives Is Worse for Greenhouse Gas Emissions in Most Cases Making the walls thicker would widen that gap further. The existing design assumes the can will be stored and consumed within a temperature range roughly between 35°F and 100°F. When consumers take it outside that window, they are operating outside the container’s design envelope, and the can was never meant to handle it.
The engineering is genuinely impressive within those parameters. A sidewall thinner than a sheet of paper routinely withstands 50 to 60 psi of internal pressure, stacking loads from palletized shipping, and the mechanical abuse of vending machines and grocery bags. It just was not built for ice.