Fridge & freezer food safety after a power outage

Quick answer

Quick answer: Health Canada says an unopened refrigerator keeps food cold for about 4 hours. A full freezer keeps food frozen for about 48 hours, and a half-full freezer for about 24 hours. Keep the doors closed. Once those windows pass, elapsed time alone is not enough: check actual temperature and, for frozen food, whether ice crystals remain.

The official 4 / 24 / 48 hour rule

These are approximate cold-holding windows, not guarantees for every appliance or every food item. They work best as a first decision point while the appliance stays closed.

What changes when you open the door?

Opening the refrigerator or freezer lets cold air escape. Health Canada therefore recommends keeping doors closed as much as possible. What the official guidance does not provide is a universal formula saying one opening costs 15 minutes, or repeated opening cuts the safe window in half.

ReadyHome treats door opening as a confidence problem, not a subtraction problem. A few brief openings add uncertainty. Repeated or prolonged opening means the unopened-appliance clock no longer describes your situation reliably, so temperature and food condition matter more.

What to check when the power comes back

Ice crystals and measured temperature

Health Canada says food that still contains ice crystals or feels refrigerator-cold can be refrozen. It may lose quality, but those condition checks are more informative than blindly extending or shortening the outage clock.

Health Canada also recommends keeping refrigerators at 4°C or below and freezers at -18°C or below during normal operation. After an outage, do not mistake the normal freezer set-point of -18°C for a universal post-outage discard threshold. The official emergency guidance specifically points to ice crystals or refrigerator-cold condition for frozen food.

What food should you throw out?

Health Canada's emergency guidance says to throw away food that has been at room temperature for 2 or more hours, and not to eat food you think may be unsafe. Bacteria do not always change smell, taste, or appearance, which is why tasting food is a lousy test.

How to keep food colder during an outage

• Keep fridge and freezer doors closed as much as possible.
• If the outage will be long, use a working refrigerator/freezer or an ice-filled cooler for important perishables when practical.
• Keep freezer food grouped together so the frozen mass helps retain cold.
• Do not put frozen food outside, even during a Canadian winter; Health Canada warns it can thaw in sunlight or become contaminated.
• A simple fridge/freezer thermometer makes the next outage easier to judge.

Want to keep the fridge powered instead?

That is a different calculation. Battery runtime needs watt-hours, appliance draw, compressor duty cycle, inverter losses, and reserve. Generator sizing also needs running and starting watts. Rather than cram those assumptions into a food-safety tool, ReadyHome keeps them separate.

• Estimate portable power station runtime.
• Size a generator for your fridge and other essential loads.
• Compare portable power station options for Canadian outages.

Methodology

The calculator uses Health Canada's approximate unopened-appliance guidance as fixed reference points: 4 hours for a refrigerator, 48 hours for a full freezer, and 24 hours for a half-full freezer. ReadyHome adds a planning warning in the last quarter of that window, clearly labelled as a ReadyHome interface choice rather than an official safety threshold.

Door opening never changes the official number in the calculator. Instead, it changes how much confidence you should place in the unopened-appliance estimate. Known temperature and freezer ice-crystal condition are surfaced as additional evidence, without claiming they guarantee every individual food item is safe.

Frequently asked questions

How long is food safe in the fridge without power?

About 4 hours if the refrigerator stays closed, according to Health Canada. After that, use actual conditions rather than assuming the food is automatically safe or automatically spoiled.

How long does a freezer stay cold without power?

A full freezer stays frozen for about 48 hours and a half-full freezer for about 24 hours if kept closed.

Can frozen food be refrozen after a power outage?

Health Canada says food that still contains ice crystals or feels refrigerator-cold can be refrozen. Quality may be reduced.

Does opening the fridge or freezer shorten the safe time?

It can make the appliance warm faster, but there is no single official number of hours to subtract. Repeated opening makes the 4/24/48-hour unopened guidance less reliable.