It sounds logical: dry ice is frozen, freezers keep things frozen, so the freezer should keep dry ice. Unfortunately, physics disagrees. Here is the short answer, the science, and the point at which buying dry ice every week stops making sense.

The short answer: no

Dry ice is solid carbon dioxide, which sits at -78.5°C (-109.3°F) and doesn't melt — it *sublimates*, turning directly into CO₂ gas. A household or standard lab freezer runs at about -18°C (0°F). To dry ice, your freezer is roughly 60°C too warm — about the same gap as between your refrigerator and a summer afternoon. The freezer slows sublimation only slightly; the dry ice still shrinks away at 2–5% per hour and is typically gone within 24 hours.

Two extra problems for anyone tempted to try:

- The thermostat trap. Dry ice can drag the freezer's air temperature below its design range, confusing the thermostat and stressing the compressor — some units shut off entirely, warming everything else inside.
- CO₂ buildup. Sublimating CO₂ displaces air. In a sealed freezer it builds pressure; in a small closed room it can create an asphyxiation hazard. Never store dry ice in an airtight container, and always keep it in a ventilated space.

How long does dry ice actually last?

In a proper insulated cooler: roughly 18–24 hours per 10 lb block. Wrapped in newspaper inside a cooler, a bit longer. In open air, hours. There is no consumer or lab appliance that "stores" dry ice long-term — the only equipment that maintains dry-ice temperatures is an ultra-low temperature (ULT) freezer.

The real question: why are you buying dry ice?

For one-off shipping, dry ice is the right tool. But many labs buy dry ice *every week* for the same three jobs:

1. Holding samples during transport between buildings or sites
2. Emergency backup when the main -80°C freezer alarms
3. Keeping a small working stock of -80°C samples near the bench

At $1–3/lb plus delivery fees plus the weekly errand, a recurring dry ice habit often costs a lab $1,500–$3,000 a year — and it fails exactly when you need it most (holiday weekends, supplier outages).

When a small ULT freezer pays for itself

A compact -86°C ULT freezer does all three jobs permanently. The [Biofargo 25L Mini ULT Freezer](https://biofargo.com/products/86-degree-small-medical-freezer-25l-portable-ultra-low-freezer) reaches -86°C — colder than dry ice — in a 46 lb benchtop chest that runs on a standard 110V outlet. Use it as bench-side working storage, as alarm-day backup, or (with a vehicle inverter) as a transport unit that never sublimates away. At $1,699, it costs less than a year of a weekly dry ice habit, and it is always full.

 Bottom line

Don't put dry ice in your freezer — it barely slows sublimation and can damage the unit. Buy dry ice for shipping; buy a ULT freezer for everything you were buying dry ice weekly for.

See the 25L Mini ULT Freezer (-86°C, $1,699)