The five numbers
| Situation | FDA's figure |
|---|---|
| Refrigerator, door kept closed | About 4 hours |
| Full freezer, door kept closed | About 48 hours |
| Half-full freezer, door kept closed | About 24 hours |
| Discard threshold | Discard refrigerated food above 40 °F |
| When to get the coolers out | If the power will be out more than 4 hours |
Source figures as printed in Document 03, §3.7, from the FDA's Food and Water Safety During Power Outages and Floods.
Ready.gov gives the same threshold from the other direction: bacteria in food grow rapidly between 40 °F and 140 °F. That range is why 40 °F is a discard line and not a suggestion (Document 03, §3.7).
What to do, in order
- Have a thermometer in the fridge and one in the freezer, before the event. The FDA is explicit about it, and it is the difference between knowing and guessing. Two cheap thermometers are the highest-value food-safety purchase in the book (Document 03, §3.7.1).
- Keep the doors shut. Every opening spends the cold. A fridge opened six times in four hours is not a four-hour fridge.
- Outage of four hours or less, doors closed: refrigerated food should be safe — but read the thermometer anyway and discard anything above 40 °F.
- Outage longer than four hours: coolers, and move what you can. Move what cannot be replaced first: refrigerated medication, infant formula, meat.
- Cook the thawing food first. A freezer is a food supply being spent. Meat that thaws and is thrown away is a loss and a morale event; the same meat cooked on day one is dinner for a week (Document 03, §3.7.1).
- Refreezing, with a thermometer: if the freezer reads 40 °F or below, the food is safe and may be refrozen.
- Refreezing, without a thermometer: the FDA says you "can't rely on appearance or odor." If the food still contains ice crystals, or is 40 °F or below, it is safe to refreeze (Document 03, §3.7.1).
What to throw out, and what to keep
The rule is the reading, not the item. Anything refrigerated that has gone above 40 °F is discarded. Anything still at or below 40 °F is kept. A freezer item with ice crystals still in it, or one reading 40 °F or below, can go back in the freezer.
Two mistakes account for most of the food that should have been thrown and wasn't. The first is trusting your nose: the FDA says plainly that you cannot rely on appearance or odour, and food that smells fine can be well inside the danger range. The thermometer decides. Nothing else decides. The second is the "just this once" exception — keeping one questionable item because it would be a shame to waste it trades a cheap piece of meat for two days of diarrhoeal illness in a household with no running water and no pharmacy. The book's standard is doubt, not proof: when in doubt, throw it out (Document 03, §3.7.2).
A fridge you cannot open
If the power is out and you are trying to stretch the cold, the doors stay shut and you eat from the shelf instead. This is why the program builds a "Layer 1" — 72 hours of food that needs no cooking, no water and no refrigeration, plus a manual can opener — before it builds anything else. Layer 1 exists partly so that the fridge decision is never a hunger decision: a household with three days of no-preparation food on a shelf will keep the door shut, and a household whose only food is in the fridge will open it (Document 03, §3.5 and §3.7.3).
Ready.gov's list is the shopping list for that layer: ready-to-eat canned meats, fruits and vegetables; canned juices; non-perishable pasteurised milk; food for infants — plus the manual can opener, which the book names as the most commonly forgotten item in the field (Document 03, §3.5).
What this page will not tell you
No shelf-life figure for dry beans, legumes or rolled oats. They are not rows in the Virginia Cooperative Extension table the book uses, so there is no sourced number, and the book prints none. Store them, rotate them, and check them for insects and moisture (Document 03, §3.6.2).
No "25-year shelf life" claim for supermarket staples. No source retrieved for the program supports multi-decade shelf lives for ordinary retail food. Those claims belong to freeze-dried food in #10 cans and to mylar-and-oxygen-absorber packaging — a different product category with its own manufacturer claims (Document 03, §3.6.3).
No calorie figure for any named food. Calories per package come off the Nutrition Facts panel on the package in your hand, which is the one number in the chapter you do not have to take on trust (Document 03, §3.4).
No cooking indoors, ever. Anything that burns happens outdoors or on a ventilated balcony — never indoors, never a garage, never a flooded basement. Carbon monoxide alarms installed and tested come before any combustion anywhere in the program (Document 03, §3.8; Document 04, §4.2).
Where a number was not available from a current source, the chapter says so and tells you who to ask instead. That is the whole standard: figures are sourced, or they are absent.