How long does a fridge or freezer last in a power cut?
The Food Standards Agency says a fridge should stay cold for up to 4 hours, and a freezer should keep food frozen for up to 48 hours if it's full, or 24 hours if it's half full, as long as the doors stay shut. It calls these estimates: makers' own tests on the freezers we looked at give 9 to 22 hours. A cut of under 4 hours is unlikely to affect your food.
Buying through our links costs you nothing extra. Some of them earn us a small commission, and that's what keeps Survival Bunker going: it pays for the time it takes to keep our picks and figures up to date. Thank you for helping. How we choose and how we earn.
The Food Standards Agency's figures
- Fridge: "should stay cold for up to 4 hours".
- Full freezer: "should stay frozen for up to 48 hours".
- Half-full freezer: "24 hours if it's half full".
- Under 4 hours: "unlikely to impact the safety of food in chilled or frozen storage".
"These are estimates. Fridge and freezer temperatures will vary depending on their make and model." Food Standards Agency: food safety in a power cut. Food Standards Scotland gives the same figures: food safety during a power cut.
What the makers' tests say
Under the energy-labelling rules, makers test how long the freezer compartment takes to warm from -18°C to -9°C once the power goes off, with the door shut. Makers print it on the spec sheet as the storage time in a power failure. For the models whose sheets we read, it runs from 9 to 22 hours:
| Model | Hours |
|---|---|
| Bosch GSN33VWEPG tall freezer | 9 |
| Bosch GSN36VWEPG tall freezer | 9 |
| Bosch KIN86VFE0G built-in fridge-freezer | 10 |
| Bosch KGN34NLEAG fridge-freezer | 12 |
| Bosch KGN392LDFG fridge-freezer | 15 |
| Bosch KGN49XLEA fridge-freezer | 16 |
| Neff G1524X7GB built-in freezer | 22 |
That's a lab test, to -9°C, so it doesn't measure the same thing as the Food Standards Agency's estimate. Other figures you'll see: National Grid's network arm says freezers "could remain cold if unopened for up to 12 hours", and Beko says food "will remain frozen for around 12 hours". Your own freezer's figure is usually in its manual or on its spec sheet.
Keep the doors shut
Every source agrees on this one. The Food Standards Agency says to "keep fridge and freezer doors closed as much as possible", and Beko explains why: it "stops warm air entering the freezer, prolonging the time it will take for the food to defrost". For a planned power cut, SSEN suggests setting the fridge-freezer to its coldest setting 12 hours before.
What to do with chilled food
The Food Standards Agency's advice for a power cut:
- "Use a fridge thermometer so you can tell if the fridge has become too warm."
- "In power cuts, food can be stored in fridges at temperatures under 8°C."
- If the fridge reaches 8°C or above, foods with a use-by date, "keep refrigerated" foods and leftovers "should be discarded after 4 hours (unless the power is restored within 4 hours)".
- "If the weather is cold (below 8°C), you can store food outside", in a sealed box, out of the sun and away from animals.
- "Food that is normally stored at ambient temperature will continue to be safe to eat."
Which? gives a stricter rule of thumb: throw out meat, fish and dairy that have been above 4°C for more than a couple of hours. The Food Standards Agency's 8°C figure is the official one for a power cut. The full Food Standards Agency advice.
How to keep a fridge-freezer running
A portable power station keeps a modern fridge-freezer going through a long cut. A 1 kWh model such as the EcoFlow DELTA 3 runs one on its own for roughly 9.9 h to 43 h, by our sizer's estimate, depending on how hard the fridge works.
| What's plugged in | EcoFlow RIVER 3 Plus | EcoFlow DELTA 3 | Jackery Explorer 1000 v2 | EcoFlow DELTA 3 Max |
|---|---|---|---|---|
| A fridge-freezer on its own | 2.8 h to 12 h | 9.9 h to 43 h | 10 h to 44 h | 20 h to 3.5 days |
| Fridge-freezer, router and 2 phones | 2.3 h to 8.9 h | 8.4 h to 32 h | 8.8 h to 33 h | 17 h to 2.5 days |
| Fridge-freezer and chest freezer | 1.5 h to 6.1 h | 5.5 h to 22 h | 5.7 h to 23 h | 11 h to 43 h |
Our estimates from the sizer, as a range from heavy to light use, allowing for the energy lost in the power station itself. A modern fridge-freezer uses 0.4-1.5 kWh a day depending on the model and the weather. Not lab figures; try your own list in the sizer.
EcoFlow DELTA 3
£649 at EcoFlowSee today's price at AmazonJackery Explorer 1000 v2
See today's price at AmazonSold out at CurrysSold out at JackeryFor your own fridge and everything else you'd want on, use What will it run? To see what else stops in your home, try Lights Out.