Quick answer
During a power outage, a closed refrigerator keeps food cold for about 4 hours. A full freezer holds its temperature for about 48 hours — a half-full freezer for about 24 hours. Every time you open the door, you lose cold air. When in doubt, throw it out. An appliance thermometer is the most reliable way to decide if food is still safe. Round up when being wrong means spoiled food.
Calculator
Estimate fridge and freezer safety during an outage
Enter your outage details below. Results update instantly in your browser. No data is sent anywhere.
Refrigerator
Within planning window if kept cold or closed
Thermometer
You have an appliance thermometer. Check actual internal temperature before deciding whether food is safe. Fridge: safe at or below 4°C. Freezer: safe at or below -18°C.
Next steps
- Keep doors closed to maintain temperature as long as possible.
- Keep the fridge and freezer doors closed as much as possible.
- If the outage continues, move critical items to a cooler with ice or a neighbour's fridge.
- Plan backup power before the next outage — not during.
Backup power notes
- Without backup power, rely on keeping doors closed and a thermometer to monitor temperature.
Door-opening adjustment is a conservative planning estimate, not official guidance. This calculator is a planning aid. Actual food safety depends on temperature, door openings, appliance condition, food type, and outage duration.
How the calculator works
The calculator starts with Health Canada's official baseline for cold-holding time and adjusts it based on door openings using a conservative planning estimate.
Official baseline
- Refrigerator: about 4 hours with the door kept closed.
- Full freezer: about 48 hours with the door kept closed.
- Half-full freezer: about 24 hours with the door kept closed.
Door-opening adjustment
Each time the door opens, cold air escapes and the internal temperature rises. This calculator applies a conservative estimate:
- Kept closed: 100% of the official baseline.
- Opened occasionally: 75% of the official baseline.
- Opened often: 50% of the official baseline.
This adjustment is a planning estimate, not official food-safety guidance. Actual temperature rise depends on room temperature, how long the door stays open, and how full the appliance is.
What the calculator does not do
- It cannot inspect your appliance, measure actual temperature, or guarantee food safety.
- It does not account for room temperature, appliance age, insulation quality, or food type.
- It is a planning aid, not a substitute for a thermometer or official guidance.
What to do during a power outage
Keep food cold checklist
- Keep the fridge and freezer doors closed as much as possible. A closed door is the best insulator you have.
- Group food together in the freezer if safe and practical. Frozen food helps keep other food frozen.
- Use a fridge/freezer thermometer to check actual internal temperature when power returns.
- Move critical perishable food to a cooler with ice or a neighbour's fridge if the outage will be long.
- Plan backup power before the outage, not during. Know your fridge and freezer wattage and have a plan.
- Discard any food that has been above 4°C for more than 2 hours. When in doubt, throw it out.
Backup power for your fridge and freezer
If power outages are a recurring problem in your area, backup power can help keep your fridge and freezer running. Here is how the common options stack up for this specific job.
Portable power stations
A portable power station (battery generator) can run a fridge or freezer for hours to days, depending on capacity and the appliance's draw. A typical fridge draws 100–200W running with a compressor surge. A 1,000 Wh station might power a fridge for 4–10 hours depending on duty cycle and efficiency. Read the full portable power station guide for sizing help.
Generators
A portable generator can run a fridge and freezer plus other essential loads during an extended outage. Size the generator for the fridge's starting surge (up to 1,200W for some models) plus any other loads. Use the generator size calculator.
UPS battery backups
Most UPS units are designed for electronics — computers, routers, servers — not fridge or freezer compressors. The starting surge of a fridge compressor can overload a UPS designed for low-draw electronics. Only use a UPS if it is specifically rated for inductive motor loads and has enough capacity. For most households, a portable power station or generator is a better fit for fridge backup.
Frequently asked questions
How long is food safe in the fridge without power?
About 4 hours if the door stays closed. After that, perishable food like meat, poultry, fish, eggs, and dairy should be discarded if the temperature has risen above 4°C. Use an appliance thermometer to check.
How long does a freezer stay frozen during an outage?
A full freezer keeps food frozen for about 48 hours. A half-full freezer lasts about 24 hours. The frozen food itself acts as thermal mass — a full freezer stays cold longer. Open the door as rarely as possible.
Should I open the fridge to check?
No. Opening the door lets cold air escape and shortens the safe window. Use an appliance thermometer visible from outside, or wait until the power returns to check the temperature.
Can a portable power station run a fridge?
Yes, if the power station is sized correctly. Check the fridge's running watts and starting surge, then compare against the power station's continuous and surge ratings. Most mid-size power stations (1,000 Wh and up) can run a fridge for several hours. Larger stations can last through a full workday or overnight.
Can I use a UPS for a fridge?
Not usually. Most UPS units are designed for electronics and cannot handle the starting surge of a refrigerator compressor. Even if the UPS can handle the surge, the runtime on a typical consumer UPS is measured in minutes for a fridge-sized load. A portable power station or generator is a better choice.
What food should I throw out after an outage?
Perishable food that has been above 4°C for more than 2 hours should be discarded. This includes meat, poultry, fish, eggs, dairy, leftovers, and cut fruits or vegetables. Hard cheeses, butter, and whole fruits and vegetables may still be safe. When in doubt, throw it out.
Is frozen food safe if it still has ice crystals?
If food still has ice crystals or is at or below 4°C (checked with a thermometer), it is generally safe to refreeze or cook. If the food has completely thawed and warmed above 4°C, discard it. Do not refreeze thawed food that has been above 4°C for more than 2 hours.
Canadian context
Canadian winters, ice storms, and summer storm seasons mean power outages are a fact of life across most provinces. Having a plan for your fridge and freezer — whether a thermometer, a cooler, ice packs, or backup power — can save you from losing a full grocery run. The official guidance from Health Canada and Public Safety Canada applies whether you are in downtown Toronto, rural Alberta, or coastal BC.
Official sources used
Public Safety Canada / Canada.ca
Canadian household outage risks and 72-hour preparedness framing.
Preventing carbon monoxide exposure
Health Canada
Generator placement, CO exposure, and fuel-burning appliance warnings.
Health Canada
Recognized Canadian certification marks and electrical product warnings.
Food and drinking water safety in an emergency
Health Canada
Official fridge/freezer outage time windows and discard guidance.