A refrigerator with its door kept closed generally keeps food cold for about four hours during a power outage. That is a planning reference, not a guarantee for every refrigerator or food. Known unsafe temperature exposure can require discarding food earlier.
The FDA’s outage guidance says to discard refrigerated perishables that have been above 40°F for two hours or more. Use a thermometer and the guidance for the actual food category. Never taste food to decide whether it is safe.
The clock and the temperature answer different questions
The closed-door reference estimates how long the refrigerator can keep food cold. A food’s temperature history determines whether it has exceeded the relevant safe holding conditions. Do not replace that history with a four-hour countdown.
For example, a hypothetical outage beginning at noon reaches the four-hour reference at 4 p.m. That arithmetic does not establish that every item is safe until 4 p.m. If you know a perishable has already spent two hours or more above 40°F, the FDA’s discard guidance applies to that exposure.
USDA’s emergency food guidance also emphasizes keeping doors closed and maintaining refrigerator temperatures at 40°F or below. Freezer time references are different; do not import them into a refrigerator decision.
Use the food-category chart
The FoodSafety.gov outage chart distinguishes foods and their keep-or-discard guidance. A condiment, a dairy product and a prepared meal should not be assumed to have the same rule simply because they shared a shelf.
Use the row for the actual item and the stated temperature and time conditions. When the history is unknown, follow the authority’s conservative guidance rather than treating the absence of a bad smell as evidence of safety. Appearance and smell cannot establish a safe temperature history.
Record what is known during the outage
| Detail | Why it matters |
|---|---|
| Outage start time | Establishes the elapsed-time reference |
| Door openings | Helps describe the actual conditions rather than assuming a continuously closed refrigerator |
| Observed temperatures and times | Supplies evidence about conditions during the outage |
| Food category | Selects the relevant chart row |
| Decision source | Keeps the keep-or-discard choice tied to the official guidance |
A reading taken only after cooling has resumed cannot reconstruct the temperature of a food during the preceding hours. Restoring mains electricity or starting backup power does not erase exposure that already occurred.
For advance power planning, the refrigerator backup-runtime guide addresses a separate calculation. A runtime estimate does not establish the temperature history or safety of food during an actual outage.
Method and limits
This guide reconciles FDA, USDA and FoodSafety.gov consumer guidance checked October 11, 2026. The noon example is hypothetical; we did not monitor an outage or evaluate your food. Keep the refrigerator closed, use the available temperature history and consult the actual food-category chart. If safety is uncertain, do not use a taste test to resolve it.
Sources
See Also
If you want to move from general advice into actual product choices, start with Portable Power Stations by Brand and Size, Solar Generator Circuit Safety Before Connecting Loads, and Best Portable Power Station for Refrigerator Backup.
For a wider picture after the basics, Battery vs Rechargeable Emergency Lanterns for Garages and Best First Aid Kit for a Cabin or Outdoor Emergency Plan are the next places to read.