Refrigerator timer for a power outage | Free online tools

Q: Where do the guideline hours come from?

From FoodSafety.gov and the USDA: about 4 hours for the fridge, about 48 hours for a full freezer and about 24 hours for a half-full one. Japanese manufacturers sometimes publish a shorter figure for the fridge, so the fridge is shown as a 2 to 4 hour range.

Q: What happens if I open the door?

The guideline hours assume the door stays shut. Every time it is opened cold air escapes and the real remaining time becomes markedly shorter than shown. This tool can log how many times you opened it, but it cannot put a number on the loss. Not opening it is what matters.

Q: Is food safe to eat while the timer is still running?

No. The hours shown are a guideline, not a guarantee of safety. If there is any sign of a problem such as an odour, a colour change or evidence of thawing, throw the food away even if time remains. Reheating does not always make food safe.

Q: Does it work with no connection?

Yes. The elapsed time is calculated from your own device clock only, with no server involved. Add it to your home screen in advance and it opens without a connection.

Q: Is the start time kept when I close the page?

Yes. The start time is stored only on your device (localStorage) and is never sent to a server. The clear button removes it at any time.

Enter the time the power went out

Start of the outage

Defaults to now. The value is stored only on your device and survives closing the page.

How full is the freezer

The more frozen items are packed in, the longer they keep each other cold.

Time since the outage started

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These figures are reference estimates based on general rules of thumb. The amount or time you actually need varies with your household, your equipment and the temperature. Always check the guidance published by your local government and by national authorities.

Not opening the door is what works

The times shown assume the door stays shut.
Every time it is opened, cold air escapes and the real remaining time becomes markedly shorter than shown. There is no reliable way to put a number on that loss, so this tool only logs how many times you opened it. However much you want to check inside, keeping it closed is the most effective thing you can do.

Times opened: 0

Deciding whether food is still edible

The times shown are a guideline. If there is any sign of a problem such as an odour, a colour change or evidence of thawing, throw the food away even if time remains.
Reheating does not always make food safe: toxins produced by bacteria can survive cooking. If you are unsure, do not eat it.

Food can be unsafe even when it looks and smells normal. And never taste food to decide whether it is safe - FoodSafety.gov and the USDA say the same. If the elapsed time does not settle the question, discard it.

Frozen food may be safely refrozen if it still contains ice crystals or has stayed at 40F (4C) or below, though the quality will suffer. Discard anything that thawed completely and stayed thawed (FoodSafety.gov / USDA).

Add it to your home screen and it opens offline

Once you have opened this page it is stored on your device and starts even with no connection. You cannot search for a page while you are out of signal, so add it to your home screen from your browser menu while you still can. Ads and analytics do not load offline, but every calculation runs on your device, so nothing breaks.

Saved on this device. It will open without a connection.

How to use this tool

Enter the time the power went out and the page shows the elapsed time plus the time remaining against the guideline for the fridge and the freezer. Everything is worked out from your own device clock, so it behaves exactly the same with no connection.

Which guideline this tool adopts, and why it shows a range

The freezer figures of about 48 hours when nearly full and about 24 hours when half full, and the fridge figure of about 4 hours, come from FoodSafety.gov and the USDA. Japanese refrigerator manufacturers sometimes publish a shorter figure for the fridge, so the fridge is shown here as a 2 to 4 hour range. If your own model has published guidance, follow that instead.

The point is not the number, it is keeping the door shut

All of these figures assume the door stays closed. Each opening raises the temperature inside and shortens what is left. The most useful thing this tool does is give you a reason not to open it.

The record stays on this device

The start time, the freezer state and the number of openings are stored only on your device, in localStorage. Nothing is sent to a server, and the clear button removes it at any time.

Frequently asked questions

Where do the guideline hours come from?

From FoodSafety.gov and the USDA: about 4 hours for the fridge, about 48 hours for a full freezer and about 24 hours for a half-full one. Japanese manufacturers sometimes publish a shorter figure for the fridge, so the fridge is shown as a 2 to 4 hour range.

What happens if I open the door?

The guideline hours assume the door stays shut. Every time it is opened cold air escapes and the real remaining time becomes markedly shorter than shown. This tool can log how many times you opened it, but it cannot put a number on the loss. Not opening it is what matters.

Is food safe to eat while the timer is still running?

No. The hours shown are a guideline, not a guarantee of safety. If there is any sign of a problem such as an odour, a colour change or evidence of thawing, throw the food away even if time remains. Reheating does not always make food safe.

Does it work with no connection?

Yes. The elapsed time is calculated from your own device clock only, with no server involved. Add it to your home screen in advance and it opens without a connection.

Is the start time kept when I close the page?

Yes. The start time is stored only on your device (localStorage) and is never sent to a server. The clear button removes it at any time.

Guidelines adopted and how the timer works
・Fridge: 2-4 hours (the upper bound is the roughly 4 hours from FoodSafety.gov / USDA; the lower bound reflects the shorter figures some Japanese manufacturers publish)
・Freezer nearly full: about 48 hours. Freezer about half full: about 24 hours (FoodSafety.gov / USDA)
・Elapsed time = now minus the start time you entered, using your device clock
・All of these assume the door is not opened. No allowance for opening it is built into the numbers.

Sources (accessed 2026-07-28)

These are the sources for the figures used here. The numbers are based on published guidance; we do not reproduce the text, tables or illustrations of those pages. Follow the links for the full explanation.

Source adopted: the guideline hours come from FoodSafety.gov / USDA. Because Japanese refrigerator manufacturers sometimes publish a shorter figure for the fridge, the fridge is shown as a 2-4 hour range rather than a single value.

FoodSafety.gov (U.S. Department of Health and Human Services), "Food Safety During a Power Outage"
https://www.foodsafety.gov/food-safety-charts/food-safety-during-power-outageThe guideline hours for the fridge and freezer that this tool adopts.
USDA Food Safety and Inspection Service, "Keep Your Food Safe During Emergencies: Power Outages, Floods and Fires"
https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/emergencies/keep-your-food-safe-during-emergenciesThe same figures, the keep-the-door-closed condition, and how to decide what to discard.
Ministry of Health, Labour and Welfare of Japan, "Food poisoning" (in Japanese)
https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/kenkou_iryou/shokuhin/syokuchu/Prevention of food poisoning, and why reheating does not always make food safe.
The blackout FAQ and manual of your own refrigeratorJapanese manufacturers sometimes publish a shorter fridge figure than the U.S. one. Always check the guidance for your model.

Primary sources are updated from time to time. Please check the linked pages for the latest wording before making any important decision. We link to public-sector material rather than reproducing it.

Before you use this tool
The figures shown here are reference information produced by general formulas. They are not guaranteed to be accurate, complete or safe. This site does not represent any government body, manufacturer or other organisation, and accepts no liability for any loss arising from the use of, or inability to use, this tool. Always check the manual for your equipment and the guidance published by the relevant authorities before acting. See our Terms and Disclaimer for details.