Keeping food safe in the fridge and freezer during an outage
How long refrigerated and frozen food stays safe during a power outage, how to limit door openings, and which foods to throw away once the power returns.
A refrigerator keeps food cold for only a few hours if its door stays shut, and a full freezer holds its temperature much longer. The most useful habit during an outage is keeping both doors closed. Every time a door opens, cold air escapes and the temperature inside climbs.
The times below follow the widely used home food safety guidance from the U.S. Department of Agriculture. They depend on how full each appliance is and how often its door is opened, so treat them as limits rather than targets.
How long food stays safe
The general limits are easy to remember. A refrigerator that stays closed keeps food safe for up to about four hours. A full freezer holds its cold for about 48 hours, and a half-full freezer for about 24 hours. Those numbers assume the appliance was properly cold when the power went out, so check the temperature rather than assuming it is still safe.
Scroll sideways to see the full table →
| Appliance | Food generally stays safe for |
|---|---|
| Refrigerator, door kept closed | Up to about 4 hours |
| Freezer, full | About 48 hours |
| Freezer, half full | About 24 hours |
Food in a fridge should stay at 40°F or below, and food in a freezer should stay at 0°F or below. A standard appliance thermometer placed inside the fridge can only be read with the door open. A thermometer with an external display or a remote sensor, which keeps the probe inside while the reading sits outside, avoids that trade-off. If you do not have one of those, a thermometer is a small addition to your emergency supplies and removes the guesswork. Read it when the door is opened anyway, such as when you take out food. A fridge that climbs past 40°F early on has less margin than one that holds steady, so the readings tell you when to move food to a cooler or start planning what to discard.
A full freezer holds its cold better than an empty one, because the frozen food absorbs heat as it warms. If the freezer is partly empty, fill the gaps with bags of ice, frozen water bottles, or other frozen containers. Dry ice is another option for keeping a freezer cold, but it needs insulated gloves, good ventilation, and a container that is not sealed airtight, because the gas it gives off builds pressure.
Limit door openings and plan ahead
Before you open the fridge, decide what you need, grab it, and close the door. Write a short list of meal ingredients and keep it on the cupboard door, so you can pull out several items at once rather than making repeated trips. Group the most perishable foods, such as meat, poultry, seafood, milk, and leftovers, so you can find and check them quickly.
A cooler helps when food needs to stay cold for longer. Fill it with ice or frozen gel packs, keep it in a shaded spot away from any generator exhaust, and keep its lid closed. Pack it with the foods you plan to use first, and check the ice each time you open the lid. Melted ice means the cold inside is warming, and that is the moment to use the most perishable items first.
If the outage looks likely to last more than a few hours, move the most perishable items into the cooler while they are still cold, rather than waiting until the fridge has warmed. Food that starts cold has more margin than food that has already spent time above 40°F, so acting early keeps more options open when the power returns.
Decide what to throw away
Once the power returns, sort your food by how cold it stayed. Perishable foods such as meat, poultry, fish, eggs, milk, soft cheeses, cooked leftovers, and cut fruit or vegetables should be discarded if they have been above 40°F for more than two hours. Refrigerated items that stayed at 40°F or below for the entire outage can be kept, though you should still check for odd smells or changes in texture.
Frozen food is more forgiving. If it still contains ice crystals, or the thermometer reads 40°F or below, it can be refrozen or cooked. Thawed perishable food that has been held above 40°F for more than two hours should be discarded, the same limit that applies to refrigerated food. A sour smell, a slimy texture, or an unusual color is a reason to throw food out even when the time limit has not passed, so meat that shows any of these goes in the trash whatever the timing.
Quality usually declines before safety does. Thawed and refrozen food can lose texture and flavor even when it is still safe, so use those items soon after the power returns. Cooking food to a safe internal temperature destroys harmful bacteria, but it does not destroy the toxins some bacteria produce. Cooking therefore cannot rescue food that was held warm for too long, and that is why the time limit matters more than how the food looks on the plate.
Shelf-stable items such as canned goods, sealed jars, and dry goods usually hold up well. Discard any can that is bulging, leaking, or deeply dented, and wipe the tops of cans before opening them.
After the outage, record the time the power went out and came back, along with the lowest and highest temperatures you saw. A short log helps with decisions about food and with any conversations with the utility or an insurer. When in doubt, throw food out, and never taste food to test whether it is safe, because tasting cannot reveal bacteria or the toxins some of them produce. Replacing food is far less trouble than dealing with a foodborne illness.