Best Before vs Use By: A Plain Guide to Food Date Labels

Two short phrases on a packet cause a surprising amount of confusion, and a fair amount of needless waste. “Best before” and “use by” look interchangeable, but they answer different questions. One tells you how good the food will be; the other tells you whether it is safe to eat at all. Learning which is which, and how to read the food itself once the printed date has passed, is one of the more useful kitchen skills going. This guide sets out what each label actually means, which dates you can treat as advice, and how to make an honest judgement when the number on the pack has come and gone.

The one distinction worth remembering

In the UK, a use by date is a safety line. It appears on foods that can make you ill if eaten too late: fresh meat and fish, cooked sliced meats, soft cheeses, ready meals and prepared salads. Manufacturers set it according to how quickly harmful bacteria are likely to grow, and it is the one date to treat as a real limit rather than a guideline. A best before date is a different animal. It marks the point up to which the food should be at its best, its flavour, texture or crunch, and says nothing about safety. Well past it, most foods have simply become a little less pleasant, not dangerous.

The practical upshot is a simple rule of thumb: use by is about safety, best before is about quality. If you remember nothing else, remember that one line. It sorts almost every item in a kitchen into “trust the date” or “trust your judgement”, and it heads off the two most common mistakes at once: eating a risky food a few days too late, and binning a perfectly good one on the strength of a quality date.

It also helps to see how differently these labels are treated across the world. In the United States, guidance from the USDA’s food safety service notes that, apart from infant formula, date labels are not required by federal law and are not reliable safety indicators. A phrase such as “Best if Used By” signals quality rather than safety, and food showing no signs of spoilage is generally fine to eat beyond it. The date is a manufacturer’s best estimate, not a switch that flips from safe to unsafe overnight.

How the date gets onto the pack

It helps to know that a printed date is a considered estimate rather than a measured fact about your particular packet. Manufacturers test how a food behaves over time under the storage conditions they expect, then set a date that leaves a comfortable margin. A best before date assumes the food has been kept as the label suggests, cool and dry, or chilled, and unopened until you reach for it. Change those conditions, by leaving something warm or opening it early, and the real quality can drift ahead of or behind the printed date. This is exactly why the number is a starting point and not the whole answer.

The same logic explains why a use by date deserves more respect. It is set around the growth of the bacteria that cause food poisoning, judged for a food stored properly and eaten by that point. Because that reasoning is about invisible microbial growth rather than taste, you cannot second-guess it by eye. The estimate built into a use by date is the safety information you are relying on, so the sensible response is to plan around it rather than test it.

Other dates you can mostly ignore

Alongside the two that matter, packaging sometimes carries a “sell by” or “display until” date. These are instructions for shop staff to manage stock rotation, not guidance for you, and a food is usually good for a while after them. If a “display until” date has passed but the use by or best before date is still ahead, go by the latter. Some items, such as loose fruit and vegetables, carry no date at all, which is a reminder that judging food by its condition is the older and often more reliable skill. Treat shop-facing dates as background noise: the date printed for you is the use by or best before.

How to judge food past its best before date

Best before dates are where most edible food gets thrown away too soon. The sensible approach is to let the food answer for itself, using three quick checks in order: look, smell, then taste a small amount.

• Look. Check for mould, a slimy surface, or any change in colour that seems off. Fizzing, bulging packaging, or a lid that has domed upward are reasons to stop and bin it.
• Smell. A sour, rancid or generally unpleasant smell is your clearest early warning. Fresh food smells clean or of very little; spoiled food tends to announce itself.
• Taste. If it looks and smells fine, a small taste will usually settle the matter. Sourness, bitterness or a stale flavour means the quality has gone, even where the food is still technically harmless.

Do the checks in that order and stop at the first one that fails: there is no need to taste something that already smells wrong. A worked example makes it concrete. Say you find a tub of natural yoghurt a week past its best before date. Look first: the surface should be even, with no fuzzy spots or pink or green patches. Lift the lid and smell: clean and milky is fine, sharp and yeasty is not. If both pass, take a small spoonful; a clean tang is normal for yoghurt, while a fizzy or bitter note tells you it has turned. Three short checks, perhaps half a minute, and you have a reliable answer that the printed date alone could not give you.

Apply these checks only to best before foods. For anything carrying a use by date, the senses are not a safe test, because the bacteria that cause food poisoning often leave no smell, taste or visible change. There the printed date, and cold storage, are what you rely on.

Common foods and what to expect

Some everyday items keep far longer than their best before date suggests, provided they have been stored well.

• Dried pasta, rice, pulses and tinned goods. These last for a long time beyond the date if the packaging is intact and dry. A dented tin is fine to use; a rusted, leaking or swollen one is not.
• Hard cheese. A little surface mould can be cut away generously, and the rest is usually good to eat. Soft cheeses are the exception, and are best discarded whole if mould appears.
• Bread. Judge it by sight and touch. Firm or stale bread toasts or makes breadcrumbs happily; visible mould means the loaf goes, rather than just the affected slice.
• Yoghurt. Often good well past its date if unopened and kept cold. A little watery liquid on top is normal and can be stirred back in; sharp sourness or fizzing is not.
• Eggs. Drop one into a bowl of water: a fresh egg sinks and lies flat, while one that floats is best discarded. Cracking it first and giving it a sniff is a reliable second check.
• Butter and hard fats. These keep well and mostly lose quality slowly rather than becoming unsafe. A rancid, paint-like smell is the sign that the fat has oxidised and is past its best.
• Flour and dried herbs. Store cupboard staples that stay usable long after the date, though flavour fades. A musty or oily smell in flour, or the sight of tiny insects, is the point to let it go.
• Bagged salad. This carries a use by date for good reason and spoils quickly once opened, so lean on the printed date here rather than a quick glance.

A general pattern runs through that list: dry, tinned and hard foods are forgiving and reward a proper look, while wet, soft and prepared foods spoil quietly and are better governed by the date. When in doubt about which group an item falls into, the label itself is the clue, because the risky foods are the ones given a use by date in the first place.

Storage does half the work

How you keep food decides how much of that best before margin you actually get. Keep the fridge genuinely cold and avoid overfilling it, so air can move around. Store older items at the front, where you will reach for them first, and put the new shopping behind them. Once a packet is opened, its printed date often no longer applies, so use it sooner and follow any “once opened, eat within” note on the label. Raw meat and fish belong on the bottom shelf, where nothing can drip onto food below, and strong-smelling items are worth covering so their flavour does not spread.

Freezing effectively pauses the clock. Bread, milk, cheese and cooked leftovers all freeze well, and freezing food right up to its use by date is perfectly safe. The date only matters again once the food has defrosted, at which point you should use it promptly and cook it thoroughly rather than treating the original number as though nothing had happened. Freezing in usable portions, a couple of slices of bread or a single meal’s worth of leftovers, means you thaw only what you need and waste none of it.

A little planning saves the most

The tidiest way to avoid the best before dilemma is to buy in a way that suits how you actually cook. A rough plan for the week, and a shopping list that follows it, means fewer items sitting in the fridge waiting to be judged. Check what you already have before topping up, and be honest about how much fresh produce you will get through, since the softest, most perishable foods are the ones most often lost. When something is nearing its date and you cannot use it in time, cooking or freezing it is almost always better than leaving it to fail. None of this is complicated, and it turns the labels from a source of anxiety into a small piece of routine information.

Why the guesswork is worth it

Reading food rather than dates is not only thrift; it is one of the simplest ways to cut household waste, and homes are the largest single source of the problem. According to the UN Environment Programme’s Food Waste Index Report 2024, households account for about 60 percent of all the food wasted worldwide, some 631 million tonnes in 2022, which works out at roughly 79 kilograms per person each year. Put another way, the report estimates that around 1 billion meals are thrown away across the world every single day.

A good share of that is food that was never unsafe, only past a quality date and binned on sight of the number. Treating best before as advice and use by as a limit, and giving doubtful items a proper look and sniff, quietly keeps a lot of good food out of the bin. It is a small change in habit that, repeated across a year of shopping, adds up to real savings and a good deal less waste. The date on the packet is a starting point for the decision, not the whole of it.