Power Cut Food Safety UK: How Long Fridge and Freezer Food Lasts

The 4 / 24 / 48 Planning Rule

Think roughly 4 hours for a fridge, 24 for a half-full freezer and 48 for a full freezer — with the doors kept closed.

The Food Standards Agency says a power outage shorter than four hours is unlikely to affect the safety of chilled or frozen food [S1].

If the outage continues, a closed fridge should stay cold for up to four hours. A full freezer can stay frozen for up to 48 hours, while a half-full freezer may manage around 24 hours [S1].

These are planning estimates, not guarantees. Appliance design, room temperature and door opening all affect how quickly food warms.

What to Do First When the Power Goes Off

Shut the doors, note the time and avoid repeated checking.

Opening a fridge or freezer lets cold air escape. Both GOV.UK Prepare and the Food Standards Agency advise keeping the doors closed as much as possible [S1][S2].

Note when the outage started. If you have a fridge thermometer, use it rather than relying only on the clock.

Turn off or unplug appliances that could be affected by a surge when power returns, following official power-cut guidance [S2].

• Keep fridge and freezer doors closed
• Write down when the power failed
• Use a fridge thermometer if available
• Check official outage updates
• Do not repeatedly open the freezer to inspect food

The 8°C Chilled-Food Threshold

Temperature matters more than the clock once chilled food starts warming.

Under normal conditions the FSA recommends keeping a fridge at 5°C or below. During a power cut, food can be stored in a fridge while it remains below 8°C [S1].

If the fridge reaches 8°C or above, foods that normally need refrigeration require faster action. The FSA advises eating those foods within four hours or discarding them after that point if they cannot be kept safely chilled [S1].

Higher-risk foods include meat, poultry, fish, ready-to-eat sandwiches and salads, deli meats, chilled leftovers and products labelled 'keep refrigerated'.

What Food Should You Use First?

Use chilled and defrosted foods before shelf-stable cupboard food.

The FSA advises prioritising foods that need refrigeration, then defrosted frozen food that does not need cooking, then room-temperature perishable foods, leaving canned, bottled and dried cupboard food until later [S1].

That order helps reduce food waste while keeping safer shelf-stable food in reserve if the outage continues.

How to Prepare Before the Next Power Cut

A thermometer, water and no-cook food make a long outage easier to manage.

GOV.UK Prepare recommends keeping bottled water and non-perishable food that does not need cooking, plus a torch, power bank and radio for power-cut preparedness [S2].

A simple fridge thermometer also gives you better evidence than guessing how warm the fridge has become.

• Fridge thermometer
• Bottled water
• No-cook shelf-stable food
• Manual tin opener
• Torch
• Power bank
• Battery or wind-up radio

Frequently asked questions

Bottom line

The safest first move in a power cut is simple: keep the fridge and freezer closed and note the time. Use the 4/24/48 figures as planning estimates, then rely on temperature and Food Standards Agency guidance for actual food-safety decisions.