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Food During a Power Outage

GridReady Guide editorial team · Updated September 2026

Keep refrigerator and freezer doors closed as much as practical and use authoritative food-safety guidance when deciding what to keep or discard.

Preserve the cold

The Red Cross states an unopened refrigerator keeps food cold for about four hours, while a full freezer can maintain temperature for about 48 hours (about 24 hours if half full).

Source: American Red Cross

When in doubt

Do not use smell or appearance alone to determine whether perishable food is safe.

Keep reading: cooking without electricity

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Updated: September 26, 2026

How long is food safe when the power is out? USDA says an unopened refrigerator keeps food safely cold for about 4 hours. A full freezer holds temperature for about 48 hours, or about 24 hours if half full, when the door remains closed.

Use temperature, not smell

USDA advises never tasting food to decide whether it is safe. Appliance thermometers help establish whether refrigeration remained at 40°F (4°C) or below. If refrigerated perishable food has not remained safely cold, follow USDA discard guidance rather than relying on appearance or odor.

Before an expected outage

Set refrigerator to 40°F/4°C or below and freezer to 0°F/-18°C or below.
Keep appliance thermometers inside both.
Freeze water containers or gel packs to add thermal mass.
Have coolers ready if refrigeration will be unavailable beyond the safe window.
Keep shelf-stable meals that need no refrigeration.

Why the clock is only a starting point

Actual food temperature depends on starting temperature, appliance insulation, room temperature, how full the appliance is and how often the door is opened. That is why an appliance thermometer is more informative than elapsed time alone. USDA's time windows are practical guidance for an unopened appliance, not permission to keep food that has become too warm.

When power returns, check temperatures before assuming everything is safe. Frozen food that still contains ice crystals or is at 40°F/4°C or below may be refrozen under USDA guidance, although quality can decline.