Quick answer
Keep fridge and freezer doors closed. An unopened fridge keeps food safe for about 4 hours. A full freezer stays cold for about 48 hours; a half-full freezer for about 24 hours. Use a thermometer to check food temperature when power returns — 4°C (40°F) or colder is safe for the fridge, 0°C (32°F) or colder for the freezer. When in doubt, throw it out.
Timing table
Food safety timing during a power outage
Refrigerator (unopened)
- Minimum
- About 4 hours
- Better
- Use thermometer to confirm temperature stays below 4°C
- Overkill
- Add ice packs or frozen gel packs to extend cold retention
Full freezer (unopened)
- Minimum
- About 48 hours
- Better
- Keep freezer full — empty space loses cold faster
- Overkill
- Add temperature data logger to track peak temp
Half-full freezer (unopened)
- Minimum
- About 24 hours
- Better
- Group frozen items together to retain cold longer
- Overkill
- Fill empty space with jugs of frozen water
Fridge/freezer combo (opened frequently)
- Minimum
- Much shorter — each opening releases cold air
- Better
- Track outage time and open only when necessary
- Overkill
- Use separate fridge thermometer with min/max recording
During the outage checklist
During the outage
- Keep fridge and freezer doors closed — this is the single most important rule
- Track when the power went out — write it down or set a phone timer
- Group cold foods together in the fridge if practical and safe
- Use a cooler with ice for essential perishables if the outage extends beyond 4 hours
- Avoid repeatedly checking food temperature — every door open lets cold air escape
- Plan backup power safely — generator or power station size matters
After power returns checklist
When power comes back
- Check fridge temperature immediately — if it stayed below 4°C (40°F), food is generally safe
- Check freezer temperature — if food still has ice crystals or is below 4°C, it can be refrozen or cooked
- Discard perishable foods that have been above 4°C for more than 2 hours
- Do not taste food to check if it is safe — taste and smell are not reliable indicators
- If in doubt, throw it out — food poisoning is more expensive than replacing groceries
- Clean up any spills from thawed meat, poultry, or fish immediately
- Restock emergency food supplies after the event
What backup power can and cannot do
- Portable power station — can run a fridge or freezer if properly sized. Check the appliance wattage and the power station’s surge and continuous output. See the portable power station guide.
- Generator — can run a fridge or freezer for extended outages. Must be used outdoors only, away from windows, doors, and vents. See generator safety Canada.
- UPS (uninterruptible power supply) — generally not sized for fridge or freezer motors. Most UPS units are designed for electronics, not compressors with high startup surge.
- Runtime calculators — the fridge/freezer runtime calculator estimates how long a power station or generator can run your appliance. Estimates are not guarantees — real-world factors vary.
What not to do
Canadian context
Power outages in Canada are often caused by events that affect wide areas — ice storms, windstorms, heavy snow, or summer thunderstorms. Extended multi-day outages are common in rural and some suburban areas. The Health Canada food and drinking water safety page provides official guidance for Canadian households.
In winter, an unheated home may keep the fridge and freezer cold longer than the standard 4-hour and 48-hour windows, but outdoor temperatures can also freeze and burst food containers. In summer, fridge and freezer temperatures rise faster in a warm home. Use a thermometer rather than guessing — temperature depends on ambient conditions, insulation, and how full the appliance is.
If you are unsure about any food’s safety, discard it. Replacing groceries is cheaper than dealing with foodborne illness.
Related links
- Fridge/freezer outage calculator
- Portable power station Canada
- Generator size calculator
- Generator safety Canada
- 72-hour kit Canada
Frequently asked questions
How long is food safe in the fridge without power?
About 4 hours if the door stays closed. Use an appliance thermometer to check: food is safe if the temperature stayed below 4°C (40°F). After 4 hours, transfer perishable items to a cooler with ice if possible.
How long is food safe in the freezer without power?
A full freezer keeps food safe for about 48 hours if the door stays closed. A half-full freezer lasts about 24 hours. Food that still has ice crystals or is at or below 4°C can be refrozen or cooked safely.
Should I throw out food after a power outage?
Check the temperature first. If perishable food has been above 4°C for more than 2 hours, discard it. Do not rely on taste, smell, or appearance — bacteria can grow without obvious signs. When in doubt, throw it out.
Can I taste food to see if it is safe?
No. Harmful bacteria do not always change the taste, smell, or appearance of food. Tasting food to check safety is not a reliable method and can make you sick.
Can a portable power station run a fridge?
Some can, but it depends on the fridge’s running watts and startup surge, and the power station’s output rating. Check the fridge nameplate for watts and the power station for continuous and surge output. Use the fridge/freezer runtime calculator to estimate.
Can I use a generator for my fridge?
Yes, a properly sized generator can run a fridge and freezer during an extended outage. The generator must be placed outdoors, away from all building openings. Use properly rated extension cords or a licensed electrician-installed transfer switch. See generator safety Canada for full safety guidance.
Sources & further reading
Check the original guidance for details that apply to your home. How we use sources
- Public Safety Canada / Canada.ca
Canadian household outage risks and 72-hour preparedness framing.
- Health Canada
Preventing carbon monoxide exposure
Generator placement, CO exposure, and fuel-burning appliance warnings.
- Health Canada
Food and drinking water safety in an emergency
Official fridge/freezer outage time windows and discard guidance.