How long is food safe in an outage? The fridge and freezer math

There is a specific set of numbers that decides whether a power outage costs you a freezer full of food, and they are published by the federal government rather than by anyone selling batteries. Four hours for a refrigerator. Twenty four or forty eight hours for a freezer, depending on how full it is. This page quotes those windows exactly, explains the conditions attached to them, and then does the only arithmetic that matters afterward: what it costs in watt hours to extend them. We have not tested any of these products, and the Amazon links above are affiliate links, disclosed at the top of this page.

The published windows, quoted rather than paraphrased

Three federal sources publish the same two windows, and it is worth seeing all three because they are worded slightly differently.

FoodSafety.gov, in its Food Safety During Power Outage chart, last reviewed August 8, 2024, states that your refrigerator "will keep food safe for up to 4 hours during a power outage," instructs you to "keep the door closed as much as possible," and says to "discard refrigerated perishable food such as meat, poultry, fish, eggs, and leftovers after 4 hours without power." On the freezer side it states that "a full freezer will hold a safe temperature for approximately 48 hours (24 hours if it is half full and the door remains closed)."

FDA, in Food and Water Safety During Power Outages and Floods, publishes the refrigerator figure as keeping food "cold for about 4 hours if it is unopened," and the freezer figure as "a full freezer will keep the temperature for approximately 48 hours (24 hours if it is half full) if the door remains closed."

Ready.gov, on its Power Outages page, last updated June 4, 2026, condenses both: "The refrigerator will keep food cold for about four hours. A full freezer will keep the temperature for about 48 hours."

Two more published rules sit underneath those windows and change the answer more often than the headline numbers do. FDA states that perishable food held at room temperature for 2 hours or more, or 1 hour if outdoor temperatures are above 90 degrees F, should be discarded. And both FDA and Ready.gov set the threshold at 40 degrees F: Ready.gov says to throw away any food that has been exposed to temperatures of 40 degrees or higher for two hours or more, and FDA says to discard refrigerated perishable food that has been above 40 degrees F for 4 hours or more.

FoodSafety.gov adds the instruction that closes the loop: "After a power outage never taste food to determine its safety."

The conditions people break first

The windows are not properties of your appliance. They are properties of a closed, cold, full box, and three things quietly shorten them.

Opening the door. Every published figure is conditioned on the door staying shut. FDA's preparation advice is to install appliance thermometers in the refrigerator and freezer before an outage, check that the freezer is at or below 0 degrees F and the refrigerator at or below 40 degrees F, and then read those thermometers when power returns. The thermometer exists so that you do not have to open the door to find out what is happening.

A half empty freezer. The gap between 48 hours and 24 hours is entirely about thermal mass. FDA's own prep list says to freeze containers of water for ice, freeze refrigerated items you do not need immediately, and group food together in the freezer, all of which are ways of buying back the difference for free.

Marketing that drops the qualifier. GE's product page for the FCM22DLWW, a 21.7 cubic foot ENERGY STAR chest freezer, advertises a "Power Outage Promise: In the event of a power outage, food remains frozen 48 hours in the freezer," footnoted to a temperature of 32 degrees F or lower. The federal 48 hour figure applies to a full freezer; GE's claim does not name a fill level. If your chest freezer is a third full, plan against the 24 hour number.

Turning the windows into watt hours

Once you decide to power the appliance rather than just close its door, the sizing question is simple, and the input is the EnergyGuide figure rather than the wattage on the nameplate.

GE publishes 346 kWh per year for the FCM22DLWW, at 115 V and 60 Hz. A year is 8,760 hours, so that is 346,000 Wh divided by 8,760, or about 39 W on average. That average already contains the compressor's duty cycle, which is why it is the right number for capacity and the amps on the spec sheet are not.

For refrigerators, our refrigerator sizing guide runs the same division across six models whose makers publish annual kWh, and the answers land between 46 W for a top freezer and 85 W for a large side by side. Take 80 W as a working figure for a full size French door or side by side, and check your own label.

So a fridge and a chest freezer together are in the region of 120 W on average. That is the load. It is much smaller than most people expect, and it is the reason food preservation is the cheapest thing a home battery does.

One caveat carried over rather than restated: no appliance maker publishes a startup surge figure for these compressors, and the evidence on what it actually is disagrees with itself by a factor of five. GE's own product Q&A on this freezer answers the question twice, once at "approximately a 5 amp draw" with "extra current during start up (approx. 2x)" and once at "approximately 4 amps" for startup, and neither answer appears on the spec sheet. The refrigerator guide works through what is and is not published there. The practical response is the same: buy output headroom, not capacity headroom, for the surge.

What these plug-in units buy you

Rated capacity divided by average load, at the ceiling. These use each unit's rated watt hours rather than usable watt hours, and they ignore inverter losses, the low voltage cutoff and the station's own standby draw, so real runtime is lower. All figures are from each maker's own spec table, read August 19, 2026.

| Unit | Rated capacity | Chest freezer alone, 39.5 W | Fridge alone, 80 W | Both, 120 W |

|---|---|---|---|---|

| BLUETTI Apex 300 | 2,764.8 Wh | 70 h | 34 h | 23 h |

| Anker SOLIX F3800 Plus | 3,840 Wh | 97 h | 48 h | 32 h |

| EcoFlow DELTA Pro 3 | 4,096 Wh | 104 h | 51 h | 34 h |

| Jackery Explorer 5000 Plus | 5,040 Wh | 128 h | 63 h | 42 h |

| EcoFlow DELTA Pro Ultra | 6,144 Wh | 156 h | 77 h | 51 h |

Read that against the published windows and the shape of the decision appears. A full freezer already gets 48 free hours. The smallest unit here adds roughly 70 more on top, at the ceiling, which turns a two day window into most of a week. A refrigerator gets 4 free hours, so almost all of the fridge column is incremental. And covering both appliances for the length of a genuine multi-day storm outage is a 4 kWh or larger job, or a smaller unit plus a way to recharge, which is what our generator pairing guide is about.

Two published details matter more at these low loads than they do anywhere else. BLUETTI publishes a 20 W idle loss for the Apex 300, which against a 39 W freezer is a third of the load again, so a station's own self consumption is not a rounding error here. And a fridge and freezer both run on cords, so unlike a furnace or a well pump, this is the rare backup job that needs no electrician at all.

The cheaper moves to make first

Before any of the above, the published guidance contains three free or near free actions that are worth more per dollar than a battery.

• Fill the freezer. FDA advises freezing containers of water for ice and grouping food together, and notes that the melting ice will also supply drinking water if your normal supply is contaminated or unavailable. This is the difference between the 24 hour and 48 hour windows.
• Buy thermometers. FDA's first preparation instruction is appliance thermometers in both the refrigerator and the freezer, so that after the outage you can determine safety by reading rather than guessing.
• Know your dry ice source. FDA publishes the sizing rule: "Fifty pounds of dry ice should keep an 18 cubic foot, fully stocked freezer cold for two days," and advises checking local sources in advance so you know where dry ice and block ice can be purchased.

If your outages are routinely under four hours, the published guidance says a closed refrigerator handles them and a full freezer handles far more, and the honest answer is that you may not need a battery for this at all. The case for one starts where the windows end.

Choosing between the picks

• You want the smallest unit that carries a fridge and a freezer through a long night and a day: the BLUETTI Apex 300 at 2,764.8 Wh, with 6,000 or more published cycles to 80 percent, the longest cell life rating of the plug-in units on this page.
• You want to push a full freezer well past the published 48 hours: any of them, and the arithmetic above shows the freezer column is where every unit looks generous.
• You want to reach a hardwired kitchen circuit rather than run cords: the Jackery Explorer 5000 Plus listing, which bundles Jackery's Smart Transfer Switch. The switch is the part that turns a box into a circuit-level answer, and the general trade is covered in transfer switch vs interlock.
• Several appliances, multiple days: the EcoFlow DELTA Pro Ultra at 6,144 Wh per battery, or the DELTA Pro 3 at 4,096 Wh with expansion to 12 kWh on one unit.

Every figure above is either a federal publication or a manufacturer datasheet claim recorded with its published basis: food safety windows from FoodSafety.gov, FDA and Ready.gov, the freezer's annual kWh and Power Outage Promise from GE's own product page, and the power station capacities from each maker's own spec table. The runtime numbers are arithmetic on those figures under the assumptions stated, not measurements we made, and not a food safety determination for your kitchen. When in doubt, the federal instruction is the one to follow: throw it out.