Food safety in a power outage: fridge and freezer rules

The short answer

Ready.gov gives two numbers to remember. A refrigerator keeps food cold for about 4 hours, and a full freezer keeps its temperature for about 48 hours, as long as you keep the doors closed. Food that reaches 40°F or higher should be thrown out. The rule is simple: "When in doubt, throw it out."

Why 40°F matters

Bacteria that cause food poisoning grow quickly above 40°F. Ready.gov advises throwing out food that has been exposed to 40°F or higher for two hours or more, or food with an unusual smell, colour, or texture. You cannot reliably tell if food is safe by looking at it or smelling it, so a thermometer is the best tool.

Place one thermometer in the fridge and one in the freezer. Look at them without opening the door if you can, or open only briefly. Ready.gov lists a thermometer, coolers, and ice among the things to have ready before an outage.

During the outage

1. Keep the doors closed. This is the most important step. Every opening lets cold air escape.
2. Group food together. A full freezer stays cold longer than a half-empty one. Fill spare space with containers of water, which you can freeze ahead of time.
3. Eat in the right order. Start with food that spoils fastest (leftovers, milk, meat, cut fruit), then the rest of the fridge, then the freezer, then shelf-stable food.
4. Use a cooler for a long outage. Pack the most perishable items with ice or frozen gel packs and keep the lid shut. Check the temperature with a thermometer.
5. Do not taste-test. Looking and smelling are not enough.

A half-full freezer warms up faster: FoodSafety.gov says about 24 hours if half full, against about 48 hours if full, as long as you keep the door closed. Your thermometer is the final word.

What to keep and what to throw out

After the power returns, check the thermometer and the time. Use this table as a guide. If the fridge was above 40°F for two hours or more, throw out perishable items.

Frozen food

If the freezer stayed full and closed, most food stays frozen for about 48 hours. If food still has ice crystals, or is at 40°F or below, it can usually be refrozen or cooked, though quality may drop. If it has thawed and warmed above 40°F for two hours or more, throw it out.

Medicine

Ready.gov says that if the power was out for more than a day, you should discard medicines that must be kept cold, unless the label says otherwise. Call your doctor or pharmacist right away for a replacement. Better still, ask them now how long your medicine can safely stay warm. Our medicine and first aid guide covers planning ahead.

Have food that needs no fridge

The easiest way to protect your family is to have food that needs no cold storage and no cooking. Canned food, dry goods, and ready-made emergency meals all work. Add a manual can opener so you are not stuck.

Keep the fridge running instead

If you want to keep the fridge itself cold, a portable power station can run a fridge for several hours. See how to run a fridge on a portable power station for honest numbers.

Next steps

• Read run a fridge on a portable power station.
• Learn how to cook without power safely.
• Follow the 72-hour blackout plan.
• Plan ahead for medicine with the home medicine guide.