When the power goes out, keep the refrigerator and freezer doors closed. FoodSafety.gov says an unopened refrigerator keeps food safe for up to about four hours. An unopened full freezer may hold a safe temperature for about 48 hours; a half-full freezer, about 24 hours. Those are planning estimates under the stated conditions, not a guarantee for every appliance or every food.
What should you do while the power is out?
- Write down when the outage began. Avoid repeatedly opening doors to check on food.
- If the outage is likely to be prolonged, prepare a cooler with ice or frozen gel packs for refrigerated perishables. Keep the cooler at 40°F (4°C) or below.
- Keep refrigerator and freezer decisions separate: a four-hour refrigerator rule is not a 48-hour rule for milk, eggs or leftovers.
| Appliance with the door kept closed | FoodSafety.gov planning window | Next check |
|---|---|---|
| Refrigerator | Up to about 4 hours | After 4 hours without power, discard refrigerated perishable food such as meat, poultry, fish, eggs and leftovers unless it was safely transferred and kept cold. |
| Full freezer | About 48 hours | Check individual items and temperature when power returns. |
| Half-full freezer | About 24 hours | Check individual items and temperature when power returns. |
When the power returns: decide food by food
Start with the appliance thermometer if you have one, then check any uncertain item with a food thermometer. Do not taste food to test its safety. FoodSafety.gov says that frozen food can generally be refrozen or cooked if it still has ice crystals or measures 40°F (4°C) or below, although texture may suffer. Partly thawed ice cream and frozen yogurt are exceptions: the FoodSafety.gov outage chart says to discard them even when ice crystals remain and they feel refrigerator-cold.
For refrigerated perishables, discard them after four hours or more without power or another safe cold source. Food moved promptly to an iced cooler and kept at 40°F (4°C) or below needs a different assessment from food left without cooling. A cold reading after power returns does not establish the earlier temperature history. Also discard perishable food that has been above 40°F (4°C) for two hours or more. When you do not know the temperature history, appearance and smell cannot prove that food is safe. Use the official FoodSafety.gov food-by-food chart for the exact category.
Milk, raw meat and cooked leftovers belong to the refrigerated-perishable category. Shelf-stable packaged food does not automatically follow the same four-hour rule, but damaged packaging or floodwater exposure requires a separate assessment.
Common questions about timing and food safety
Four hours or two hours: which clock applies?
Four hours is an estimate for a closed refrigerator; two hours concerns perishable food above 40°F (4°C). Do not add them into a six-hour allowance.
If the freezer was still partly frozen after 24 hours, must I throw everything out?
No. Check for ice crystals or a measured temperature of 40°F (4°C) or below, then consult the category-specific chart. The 24-hour figure is an estimate for a half-full freezer with its door closed; it is not an automatic discard deadline.
Can I keep milk because it smells normal?
No smell test can replace the time and temperature decision. If it was refrigerated and the power has been out for four hours or more without another safe cold source, follow the discard guidance for perishable food.
For a check you can make before an outage, see our guide to checking the refrigerator with a thermometer.
For the next outage, keep appliance thermometers in both compartments, note when power fails and returns, and have a cooler and ice ready if you expect a long interruption. The cooler itself must keep perishables at 40°F (4°C) or below.
Sources
- FoodSafety.gov, Food Safety During Power Outage — refrigerator, freezer and food-by-food decisions.
- FoodSafety.gov, Avoid Foodborne Illness During Temporary Power Outages — closed-door windows and cooler preparation.
Reviewed 28 September 2026. If flooding or another contamination event affected food, use the specific emergency guidance rather than this power-only checklist.
FoodSafety.gov food-by-food chart · CDC guidance on keeping food cold during an outage
Clarifications checked: 18 October 2026.