How Long Does Food Last Without Power?

This guide focuses on refrigerated and frozen food during a household power outage. It does not cover every shelf-stable food, infant-feeding situation, or food affected by flooding.

A power outage does not make every food unsafe immediately, but the food temperature and the time without reliable refrigeration matter. Keep the refrigerator and freezer doors closed, record when the outage began, and use a food thermometer when one is available.

Quick Answer

An unopened refrigerator generally keeps food cold for about 4 hours. After that, check the food temperature and follow current USDA or FDA guidance for perishable food.

A full freezer may hold its temperature for approximately 48 hours, and a half-full freezer for approximately 24 hours, when the door stays closed. These are planning timeframes for a closed appliance, not a guarantee that every item remains safe.

The 4-hour refrigerator figure is not the same as saying food may be above 40°F for four hours. It is an estimate of how long an unopened refrigerator may keep food cold after the power fails. FDA recommends keeping the refrigerator at or below 40°F; if perishable food has been above that temperature, use the applicable USDA or FDA guidance for that food.

Food situation	What to do
Unopened refrigerator after about 4 hours without power	Check food temperature and follow current USDA/FDA discard guidance
Full freezer with the door closed	Use approximately 48 hours as a general holding estimate
Half-full freezer with the door closed	Use approximately 24 hours as a general holding estimate
Perishable food has been above 40°F	Apply the relevant USDA/FDA food-safety guidance; do not infer safety from the outage duration alone
Temperature history is unknown	Use a conservative decision and do not rely on smell or appearance

The most useful immediate action is simple: keep the doors closed.

How Long Does Food Last in a Refrigerator?

An unopened refrigerator generally keeps food cold for about four hours after power is lost. The estimate assumes the door stays closed as much as possible. Room temperature, how full the refrigerator is, door openings, insulation, the starting temperature of the food, and the condition of the appliance can all change the result.

FDA recommends keeping a refrigerator at or below 40°F. That storage threshold should not be turned into a simple “four hours above 40°F” rule. If you know that perishable food has been above 40°F, use the applicable USDA or FDA guidance for the food and the exposure history.

Foods needing particular attention include:

• Meat and poultry
• Seafood
• Milk and cream
• Eggs
• Soft cheeses
• Leftovers
• Cooked foods
• Cut fruit and vegetables
• Deli foods

If the outage began while you were away, you may not know how warm the food became. In that situation, use the safest applicable official guidance rather than guessing from smell, appearance, or how cool a container feels.

How Long Does Food Last in a Freezer?

A freezer generally holds cold longer than a refrigerator because frozen food starts at a lower temperature and the compartment is insulated.

USDA and FDA emergency guidance gives these approximate timeframes when the freezer remains closed:

• Full freezer: about 48 hours
• Half-full freezer: about 24 hours

Keep the freezer closed. Opening the door releases cold air and may shorten the holding time.

FDA guidance indicates that food that still contains ice crystals, or is at 40°F or below when checked, may be safely refrozen or cooked, although quality may decline. If food has completely thawed and its temperature history is uncertain, consult the relevant USDA or FDA guidance for that food.

Do not taste food to decide whether it is safe.

What to Do During a Power Outage

1. Keep the doors closed. Avoid opening the refrigerator or freezer to check food repeatedly.
2. Record the outage start time. This gives you a reference point when you apply official guidance.
3. Prepare a cooler if the outage may continue. Use ice or a properly used cooler according to official instructions, and keep raw meat and seafood separate from ready-to-eat food.
4. Check temperature when possible. A food thermometer provides more useful information than guessing from how a container feels.
5. Separate refrigerated and frozen food decisions. The holding times and official guidance are different.
6. Check the manufacturer’s instructions. Some appliances include temperature alarms or emergency guidance that can help you understand what happened.

A Simple Food-Safety Decision Path

Use this sequence when you need to make a decision quickly:

1. Was the refrigerator or freezer kept closed?
2. When did the power fail, and when was it restored?
3. Do you know the temperature of the food or appliance?
4. Is the item perishable, frozen, or shelf-stable?
5. Which USDA or FDA guidance applies to that food?
6. If safety cannot be established, can you discard the food rather than guess?

Food situation	Recommended action
Refrigerator stayed closed and the outage was short	Check temperature and food type before keeping perishable food
Perishable food exceeded the applicable safe-temperature guidance	Discard it
Frozen food still has ice crystals or is 40°F or below when checked	It may be refrozen or cooked under FDA guidance; quality may decline
Temperature history is unknown	Use a conservative decision
Food was exposed to floodwater	Discard it and follow official contamination guidance

When Should You Discard Food?

Discard food when:

• It exceeded the applicable USDA or FDA temperature and time guidance.
• The outage lasted beyond the relevant appliance guidance and no reliable temperature information is available.
• Its temperature history cannot be established safely.
• Packaging is leaking or damaged.
• The food was exposed to floodwater or another contaminant.
• The food is intended for an infant, an older adult, a pregnant person, or someone with a weakened immune system, and safe handling cannot be confirmed. Follow the relevant official guidance for that situation.

When safety cannot be confirmed, discarding the food is the safer choice. Cost, appearance, and how much food is in the package do not change the applicable food-safety guidance.

Why Smell and Appearance Are Not Enough

Harmful bacteria may not produce a strong odor or visible change. USDA guidance warns against using taste, smell, or appearance as the only test for safety.

Never taste food to “test” it. This matters especially for cooked meat, dairy, seafood, leftovers, infant food, and food prepared for people who may be more vulnerable to foodborne illness.

What to Do When Power Returns

1. Check that the refrigerator and freezer are operating normally.
2. Confirm that the refrigerator returns to a safe temperature.
3. Check food temperature if possible.
4. Separate items that need closer review.
5. Discard food that exceeded the applicable safety limit.
6. Clean spills or leaking packages.
7. Follow USDA or FDA guidance for refreezing.

Restoring power does not make previously unsafe food safe again.

How Backup Power Fits Into Food Safety Planning

Backup power may help maintain refrigerator operation during a longer outage, but food safety decisions still depend on temperature, appliance operation, outage duration, door openings, and food type.

Need to plan backup power for your refrigerator? Read Refrigerator Outage Calculator to estimate the required output and battery capacity. The result is a planning estimate and should be checked against your refrigerator and power-system manuals.

This article explains food-safety decisions. It does not calculate battery capacity or guarantee refrigerator runtime.

FAQ

How long does food last in the fridge without power?

An unopened refrigerator generally keeps food cold for about four hours. After that, check the food temperature and follow current USDA or FDA guidance. The four-hour appliance estimate is not a rule that food may be above 40°F for four hours.

How long does food last in a freezer without power?

A full freezer may hold its temperature for approximately 48 hours. A half-full freezer may last approximately 24 hours if the door remains closed. Check individual food items when power returns.

Can frozen food be refrozen after a power outage?

Food that still contains ice crystals, or is at 40°F or below when checked, may be safely refrozen or cooked under FDA guidance, although quality may decline. If the food is completely thawed and its temperature history is unknown, use the applicable official guidance.

Can I tell if food is safe by smelling it?

No. Harmful bacteria may not change the smell, taste, or appearance of food.

What should I do if I am unsure?

Follow the relevant USDA or FDA guidance. When the temperature history cannot be established safely, use a conservative decision and discard the food.

Sources

• USDA FSIS, “Keep Your Food Safe During an Emergency”
• FDA, “Food and Water Safety During Power Outages and Floods”
• FDA, “Power Outages: Key Tips for Consumers About Food Safety”
• FDA, “Are You Storing Food Safely?”
• FDA, “Refrigerator Thermometers: Cold Facts About Food Safety”