Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
When the power fails, refrigerated and frozen food are at risk. Use temperature readings and ice crystal presence to decide what is safe to eat and what must be thrown away. The safety window depends on how full your freezer is and how long the door stays closed.
Necessary equipment
| Item | Note |
|---|---|
| Refrigerator thermometer | An accurate thermometer shows the actual temperature inside your refrigerator. |
| Freezer thermometer | An accurate thermometer shows the actual temperature inside your freezer. |
| Dry ice or block ice (optional) material | Use the ice to keep food cold if power will be out for more than a few hours. |
Specifications
Source: Food and Water Safety During Power Outages and Floods · tier 1 · accessed 2026-08-03
Source: Food and Water Safety During Power Outages and Floods · tier 1 · accessed 2026-08-03
Source: Food and Water Safety During Power Outages and Floods · tier 1 · accessed 2026-08-03
Source: Power Outages: Key Tips for Consumers About Food Safety · tier 1 · accessed 2026-08-03
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
During the power outage
Estimated 5 min
- KEEP THE REFRIGERATOR DOOR CLOSED during the power outage.<1mReport a problem with step 1, During the power outage
- Food in an unopened refrigerator stays cold for approximately 4 hours
- KEEP THE FREEZER DOOR CLOSED during the power outage.<1mReport a problem with step 2, During the power outage
- A full freezer maintains safe food temperature for 48 hours
- A half-full freezer maintains safe food temperature for 24 hours
- OBTAIN DRY ICE or block ice if the power outage will last longer than a few hours.5mReport a problem with step 3, During the power outage
After power returns
Estimated 2 min to 4 min
- INSERT A THERMOMETER into the coldest part of the refrigerator.1mReport a problem with step 1, After power returns
- Read the temperature.
- INSERT A THERMOMETER into the coldest part of the freezer.1mReport a problem with step 2, After power returns
- Read the temperature.
Decide what to keep or throw away
Estimated 8 min to 15 min
FOOD AT UNSAFE TEMPERATURES CAN CAUSE FOODBORNE ILLNESS.
DO NOT TASTE FOOD TO DETERMINE IF IT IS SAFE.
- DISCARD ALL REFRIGERATED PERISHABLE FOOD if the refrigerator temperature is above 40 degrees F.3mReport a problem with step 1, Decide what to keep or throw away
- Discard all meat
- Discard all poultry
- Discard all seafood
- Discard all milk
- Discard all eggs
- Discard all leftovers
- KEEP REFRIGERATED PERISHABLE FOOD if the refrigerator temperature is 40 degrees F (4 degrees C) or lower.<1mReport a problem with step 2, Decide what to keep or throw away
- The food is safe if the temperature stayed at 40 degrees F or lower throughout the outage.
- EXAMINE EACH FROZEN PERISHABLE ITEM for ice crystals.5mReport a problem with step 3, Decide what to keep or throw away
- Look at the food itself, not the freezer thermometer.
- KEEP FROZEN FOOD if it still contains ice crystals or feels 40 degrees F (4 degrees C) or below.<1mReport a problem with step 4, Decide what to keep or throw away
- This food is safe. You can refreeze it or cook it.
- DISCARD FROZEN PERISHABLE FOOD if it shows no ice crystals and feels warm.<1mReport a problem with step 5, Decide what to keep or throw away
- The food is warm and is no longer safe to eat
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- power outage
- Also called: no common alternatives
- perishable food
- Also called: no common alternatives
- ice crystals
- Also called: no common alternatives
- foodborne illness
- Also called: no common alternatives
When to use a professional
CONSULT A PHYSICIAN if you develop nausea or vomiting or diarrhea or cramps or fever after you eat unsafe food.
Common questions
How long does my freezer stay cold when the power is out?
A full freezer stays cold for about 48 hours (2 days) if you keep the door closed. A half-full freezer stays cold for about 24 hours (1 day). Once you open the door, the time gets much shorter.
Can I refreeze thawed food?
Only if the food still contains ice crystals or feels as cold as a refrigerator (40°F or below). If the food has completely thawed and feels warm, do not refreeze it or eat it. Throw it away.
Should I taste food to see if it is safe?
No, never. You cannot tell if food is safe by tasting it, smelling it or looking at it. Foodborne illness bacteria do not change how food looks, smells or tastes. Use temperature and ice crystals only.
What if the power is out for longer than 4 hours?
An unopened refrigerator holds food cold for about 4 hours - that is FDA's figure for how long the appliance keeps up, not permission to eat what is inside afterwards. For the food itself, FDA publishes two different discard times: two hours above 40 F in its Key Tips guidance, and 4 hours at refrigerator temperatures above 40 F in its Power Outages and Floods guidance. We publish both rather than averaging them, because they are both FDA's. If you cannot tell which applies to you, use two hours - it is the one that does not make you ill if you guess wrong. Judge freezer food by ice crystals, not by the clock, and never taste anything to decide.
Where should I put a thermometer so it shows the real temperature?
Put the thermometer in the coldest part of the refrigerator or freezer. This is usually near the back or bottom. A thermometer near the door will show a warmer temperature because the door opens often.
What symptoms of food poisoning should I watch for?
Foodborne illness can cause nausea, vomiting, diarrhea, stomach cramps and fever. Symptoms usually start between 1 hour and 72 hours after eating unsafe food. Call a doctor if these symptoms appear.
Related procedures
- How to get the house ready for a storm and a power outage
- How long should you wait before plugging in a refrigerator after it is moved or delivered?
- Why has my fridge ice maker stopped making ice?
- How do I know if my meat thermometer or fridge thermometer is accurate, and how do I calibrate it?
- What temperature should my fridge and freezer be set to?
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1Food and Water Safety During Power Outages and Floods
- Tier 1Avoid Foodborne Illness During Temporary Power Outages
- Tier 1Power Outages: Key Tips for Consumers About Food Safety
Revision history
Current version 1 · updated 2026-08-03 · next review due 2027-08-03
- v1 · 2026-08-03First publication.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.