What Do Expiration Dates Mean — and Who Decides Them

You are standing at the open fridge with a tub of yoghurt, reading a date that passed three days ago. It looks fine. It smells fine. Into the bin it goes anyway, because the little stamp says so. That flicker of doubt, repeated in millions of kitchens, is worth pausing on — because what do expiration dates mean is not what the packaging implies.

In the United States, the date on your food certifies far less than most shoppers assume. With a single exception, no federal law requires it or dictates what it says. Nearly every date stamped on a package is the manufacturer’s own estimate of peak quality — the last day the product is judged to be at its best, not the day it turns dangerous.

That gap, between what the date implies and what it actually guarantees, is the whole story. It explains why the phrases contradict each other from one aisle to the next, why mountains of edible food end up in the bin, and why federal agencies have spent years trying to tidy the system up.

The date is a guess, not a deadline

Start with the thing almost nobody is told: the date is chosen by the company that made the food, using its own testing and commercial interest. A cereal brand decides when its flakes stop being pleasantly crisp. A sauce maker decides when the colour has drifted too far from the shade it wants. Neither is telling you the moment the food becomes a health risk.

Manufacturers reach these dates through shelf-life studies — storing samples under expected conditions and checking, at intervals, when taste, texture or appearance falls below the standard they will defend. The result is a quality forecast dressed up as a fact. It runs conservative, because a brand would far rather you throw out a good product than eat a stale one and blame the label.

None of that makes the date meaningless — it means something narrower than the word “expiration” suggests.

Who actually sets the date

Here the American system diverges from what people picture. There is no central office stamping approval on food dates the way there is for drug dosages or aircraft parts. Outside one narrow category, the government neither requires a date nor polices the words printed next to it.

The Department of Agriculture oversees meat, poultry and eggs; the Food and Drug Administration covers most other packaged food. On dating, both have long held the same line: it is voluntary, and it signals quality rather than safety. States then fill the vacuum with their own patchwork rules, so a “sell by” that is mandatory in one state can be optional across the border.

The result is a market where a maker can print “sell by”, “best by”, “enjoy by”, “guaranteed fresh” or nothing at all, and every version of that is legal. The words look official. Almost none of them are defined in law — an everyday standard that is not standardised, much like why clothing sizes are inconsistent from one brand to the next.

What each phrase is trying to tell you

The phrases are not interchangeable, even though shoppers tend to read them as one blunt “throw it out now” signal. Each is aimed at a slightly different reader, and only one of them is really addressed to you.

Read that way, most of the dates on your food were never addressed to you at all. A “sell by” is a message from the manufacturer to the shop’s stockroom. You are reading someone else’s mail and treating it as a verdict on tonight’s dinner.

The one date that is the law

There is exactly one product on an American shelf whose date carries the force of federal regulation: infant formula. The FDA requires a “use by” date on it, and that date means what people wrongly assume every date means. After it, the formula should not be fed to a baby, because the maker can no longer guarantee the nutrient levels the label promises.

That lone exception is revealing. The government mandates a hard date precisely where the stakes are high and the consumer — an infant — cannot look at the food and decide for themselves. Everywhere else, the logic runs, an adult can use their eyes and nose.

It is the same instinct that shapes how the FDA approves medical devices: strict rules where harm is likely, a far lighter touch where it is not. Food dating simply sits at the permissive end of that spectrum, and infant formula is the one place it does not.

Quality and safety are not the same thing

The confusion that wastes the most food is the quiet collapse of two separate ideas into one. Quality is whether food is pleasant — crisp, fresh-tasting, the right colour. Safety is whether it will make you ill. The two decline on completely different clocks, and the date on the package is nearly always tracking the first while shoppers read it as the second.

Canned beans lose a little texture over years while staying perfectly safe to eat. A bag of pre-washed spinach, by contrast, can look and smell fine and already carry enough bacteria to make someone sick. In neither case does the printed date really speak to the danger; it was set for the beans, not the spinach, and it treats them the same.

Safety is driven far more by handling than by the calendar. Whether the food was kept below 40°F, whether raw juices dripped onto something ready to eat, how many hours a cooked dish sat out at a summer barbecue — those things decide risk, and none is written on the label.

A yoghurt two days past its “best by” and kept cold the whole time is a quality question. The very same yoghurt left out all afternoon is a safety one, whatever the stamp says.

Why the labels drive so much waste

The cost of all this ambiguity is enormous, and most of it lands in the bin. The Environmental Protection Agency estimates that in 2019 the country generated about 66 million tons of wasted food in homes, restaurants and shops — a large share of it still edible on the day it was thrown out.

Date confusion is a real slice of that total. The FDA has said misreading date labels is thought to account for roughly 20 percent of consumer food waste in the home, which is why in 2019 it publicly backed an industry effort to standardise the wording. When a “best by” reads as a safety cliff, people obey it, and good food dies for nothing.

The EPA has put the underlying problem plainly, noting that date labels are ambiguous about whether they refer to quality or safety, which leaves shoppers and food banks alike to make their own call. That guesswork is expensive and, unlike much of what fills a landfill, avoidable.

The waste does not stop at the household. Most discarded food ends up buried, where it rots and releases methane, which is why food waste keeps turning up alongside packaging in arguments about what happens to the things we throw away and the wider waste stream.

How to tell if food has really gone off

If the date is only a quality guess, what should you actually trust instead? For most foods, your own senses and a few habits of storage do more work than the stamp ever could. This is the practical part the label leaves out.

• Look and smell before anything else: sour odours, a slimy film on meat, fizzing in a sealed jar or a bulging can are real warnings, and no date on earth overrides them.
• Keep the fridge at or below 40°F. Cold, not the calendar, is what slows spoilage and the growth of the bacteria that actually make people ill.
• Be stricter with high-risk foods — raw meat, seafood, soft cheeses, cut melon, prepared deli items — than with shelf-stable tins and dry goods.
• When something has sat out warm for hours, judge it by that, not by a date that quietly assumed it was kept cold the whole time.

An explainer has to be honest about its limits here. Your senses catch spoilage bacteria, the kind that announce themselves with smell and slime. They do not catch the pathogens behind the worst foodborne illness, which often leave food looking and tasting entirely normal. “When in doubt, throw it out” survives precisely because sight and smell are imperfect instruments, and caution here is not waste.

What is changing

The system is being tidied slowly, and mostly by pressure rather than by law. Industry groups have pushed a two-phrase standard: “Best if Used By” for everyday quality, and “Use By” held back for the handful of products where safety genuinely lapses. The aim is to collapse a dozen competing phrases into two with clear, separate jobs — a fix for confusing shelf life labelling.

Regulators are edging the same way. In December 2024 the Agriculture Department’s Food Safety and Inspection Service and the FDA jointly asked the public for information on date labelling and its link to food waste — the groundwork a formal rule is usually built on. California has gone further, becoming the first state to require standardized wording and phase “sell by” off consumer packaging.

Until that settles, the sensible habit is to read the date for what it is. It is a manufacturer’s opinion about peak quality, not a safety deadline set by the state. Check the words, trust your senses, keep things cold, and be strict only where the risk is real. The stamp is information, and it is useful. It was never meant to be an order.