Emergency preparedness guide

How long would UK supermarkets last in a crisis?

The short answer: nobody knows for certain. The popular claim that Britain is "three days from empty shelves" is not backed by good evidence. But fresh food would go first, within days. And even after a problem is fixed, shelves can take weeks to recover.

Supermarkets run on a "just in time" system. They hold little spare stock on purpose, because stock costs money. That makes the food supply efficient in normal times, and quick to feel any disruption.

What the evidence says

• Not three days. Full Fact looked for evidence for the "three days from empty shelves" claim and found none. It reports that grocery retailers hold roughly ten days of stock in their warehouses, not counting fresh and chilled food, and not counting some smaller retailers.
• But some food is very short-lived. Which? reported in 2020 that most grocery supply chains hold around four weeks of stock, but as little as 24 hours' worth for some fresh products, and that supermarkets themselves store barely anything beyond what is on the shelves.
• Stock in a warehouse is no use if it cannot move. Lorries need to be told where to go, shops need to place orders, and tills need to take payment. A failure of data, payments or fuel can empty shelves even when food exists somewhere in the system.
• We import a lot. The National Audit Office put the UK's food self-sufficiency at around 60% in 2025, which means roughly two-fifths of our food by value comes from abroad. Its September 2026 report also found UK households less prepared for emergencies than those in several other countries.

What would go first

The realistic picture is uneven, not a cliff edge. Fresh and fast-selling lines, such as bread, milk and salad, would run short within days or sooner. Tinned, dried and long-life food would last longer. The first problems would be gaps and rationing of particular items, not bare shelves everywhere at once.

Panic buying turns a delay into a shortage

During an earlier UK fuel crisis, Just Food reported that some supermarkets saw sales jump by 300%. One deputy manager said that if customers had simply bought what they wanted, the shop would have sold out of bread by 10am. Tesco limited customers to three loaves and Safeway to one, and industry bosses thought it could take up to three weeks for the logistics to catch up.

That last figure is the one to remember. Even after the cause is fixed, shelves recover in weeks, not days.

What to do

• Build a buffer slowly, before anything happens. Add one or two extra items to every normal shop. Choose food you would eat anyway. It costs little, and you are not one of the people emptying the shelves for everyone else.
• Aim for two weeks as a sensible minimum. The government's Be Ready advice says three days. Because recovery takes weeks, two weeks is a safer margin. As a rough guide, an adult needs 2,000 to 2,500 kcal a day, so two weeks is about 28,000 to 35,000 kcal per person.
• Think about cooking. Rice, pasta and pulses are cheap and filling but need water and fuel. Keep some food that needs no cooking at all: tinned meat, fish and beans, nut butters, crackers and cereal bars. And buy a manual tin opener.
• Keep some cash. If card readers go down, shops that cannot take cards may not be able to sell you anything.
• If shelves start to empty, stay at home. Anxious crowds competing for the last items are a risk in themselves. A household that has prepared never needs to be there.
• Rotate your stock. Write the purchase date on tins and eat the oldest every 6 to 12 months, so nothing goes to waste.

Our free printable checklist has quantities per person for three days and two weeks.

• Free printable checklist: preparing beyond three days
• How much water do you need per person in a power cut?
• The government's Be Ready advice: what it covers, and what it leaves out