Sell-By Dates Are Not What You Think

It's Friday, October sixteenth. If you threw away a yogurt this week because the date on the lid was yesterday, you are not alone. Tens of millions of Americans did the same thing, and almost all of them threw out food that was perfectly fine to eat. Not "fine" as in you probably won't get sick. The Food and Drug Administration has said this directly: those dates are not about safety. They are about when the manufacturer thinks the product tastes best. And in most cases, the manufacturer can pick whatever date it wants, because there is no federal law that says otherwise.

Confusion over these labels causes an estimated 20 percent of consumer food waste in the United States. That is roughly three billion pounds of food thrown out every year, not because it's spoiled, but because of a little date stamp that almost everyone misunderstands. The system that created those dates is barely fifty years old, was invented by a British department store, and in the entire history of the United States has never been regulated at the federal level for most food. Until this year. California just became the first state to force standardization. And the story of how we got here, from a London stockroom in the early 1970s to your refrigerator right now, is not what you would expect.

The sell-by date does not come from some federal food safety agency. It comes from Marks and Spencer, the British department store. In 1970, M&S began printing dates on the wrappers of its food products inside its storerooms, an internal system to help staff rotate stock. The dates weren't for customers. They were for employees to know which box of biscuits to put on the shelf first. Two years later, in 1972, the company decided to put those dates on the packaging that customers could see, positioning them as a guarantee of freshness. M&S was so proud of this that the slogan "the sell-by date means that St Michael foods are fresh" appeared on its shopping bags.

The innovation spread. Other retailers adopted it. The British government eventually made it a legal requirement. But there is a difference between what happened in Britain and what happened in the United States, and that difference is everything.

In the United States, sell-by dating remained almost entirely voluntary. The only product for which federal law requires a date label is infant formula. That's it. For everything else, milk, eggs, yogurt, bread, cheese, meat, manufacturers can date it however they want, with whatever language they want, or not date it at all. The result is something close to chaos. According to the Consumer Brands Association, there are more than fifty different date label phrases used on food packaging in the US: "sell by," "use by," "best by," "best if used by," "enjoy by," "fresh until," "use or freeze by," "expires on," and dozens more.

Almost none of them mean what people think they mean.

There are really only three functions a date on food packaging can serve. One is for the store's inventory management: that is the "sell by" date, telling the retailer when to pull the product off the shelf. One is about quality: that is the "best if used by" date, indicating when the manufacturer thinks the product will be at its peak taste and texture. And one is about safety: the "use by" date, indicating a point after which there is some actual increased risk. The problem is that consumers cannot tell which is which, and the evidence on this is overwhelming.

A 2007 FDA-commissioned survey found that less than half of American consumers could distinguish between the meanings of "sell by," "use by," and "best if used by." A 2016 survey by Harvard's Center for Health Law and Policy Innovation found that more than a third of consumers wrongly believe that date labels are federally regulated, and another 26 percent are unsure. Eighty-four percent of consumers said they throw out food based on date labels at least occasionally.

What does this actually look like in a refrigerator? The USDA says eggs are safe for three to five weeks after the sell-by date. Its own research found eggs can still be Grade A quality after fifteen weeks in proper refrigeration. Milk typically lasts five to seven days past the sell-by date. A 2023 study in a peer-reviewed journal found that whole milk showed no significant bacterial increase five days after its expiration date, and fat-free milk showed no significant increase even ten days after. Canned goods can last years past any printed date, as long as the can is not rusted, dented, or swollen.

But the confusion is not just theoretical. Montana requires milk to be sold within twelve days of pasteurization. Idaho, the state next door, allows up to twenty-three days. The same product, the same science, and a difference of nearly two weeks, based on nothing but which state line the grocery store happens to be on.

If the solution is just to standardize the labels, why hasn't anyone done it? People have been trying for decades, and the obstacles are not what you would guess.

Part of the answer is that the current system is convenient for manufacturers. When a food company can set its own date, it can set it conservatively, earlier than necessary, so that the consumer always eats the product at its absolute peak. That protects the brand. No one ever blames a yogurt company for setting the date too short. They only blame it if the yogurt goes bad before the date. So there is a one-way incentive: make the date as short as you can get away with. Andy Harig, a vice president at the Food Marketing Institute, put it directly: "You want people to eat and enjoy the product when it's at its peak, because that's going to increase their enjoyment and encourage them to buy it again."

The other part is that the federal government has stayed out of it by design. The FDA and USDA have issued voluntary guidance. They have encouraged manufacturers to use "Best if Used By" for quality and "Use By" for safety. But they have never required it, and Congress has never passed a law. The Food Date Labeling Act, which would create a national standard, has been introduced multiple times and has never made it through.

California decided to go around the federal government entirely. In September 2024, Governor Newsom signed Assembly Bill 660, authored by Assemblymember Jacqui Irwin. It took effect on July 1st of this year, 2026. It requires any food item manufactured after that date, if it carries a date label at all, to use exactly two phrases: "BEST if Used by" for quality, and "USE by" for safety. The law bans consumer-facing "sell by" dates outright. More than fifty different phrases, collapsed into two. California is the first state in the country to do this.

ReFED, a nonprofit that studies food waste economics, estimates that standardizing date labels nationally could divert between 381,000 and 582,000 tons of food from landfills each year, with an economic value of roughly two billion dollars. That puts it among the most cost-effective food waste interventions available. The cost to implement is almost zero. Manufacturers just change the text on the label. The benefit is that perfectly edible food stays out of the trash.

There is one more dimension to this, and it is the one that makes the whole system feel slightly absurd once you see it. For almost all of human history, people decided whether food was safe to eat by looking at it, smelling it, and tasting it. Those senses still work. The FDA says this directly: if a food does not show signs of spoilage, it is safe to consume past the date on the label. The date is a guideline about quality, not a verdict about safety.

The science backs this up in specific terms. Milk spoils in a way you can detect. It smells sour, it curdles in your coffee, your body recoils from it before you can swallow. Eggs float in water when they are past their prime because the air cell inside has expanded. Bread goes hard or grows visible mold. Yogurt gets watery but that is just whey separation, not spoilage. These are signals your senses were built to read.

The reason this matters is not just about saving money, though an average American family of four throws out roughly three thousand dollars worth of food each year. It is about the fact that a system built for a British department store's stockroom in 1970 now governs what tens of millions of Americans put in their trash every night, and almost none of them know where it came from or what it actually means. The labels have the appearance of scientific authority, of regulatory oversight, of some kind of official safety determination. They have none of those things. They are a brand-protection tool, dressed up as a public health measure, and nobody asked you whether you wanted it.

California's new law is a real fix, and if it works the way advocates expect, other states will follow. But the bigger change is simpler than any legislation. The next time you look at a date on a package, ask yourself: is this telling me something about safety, or is it telling me something about what the manufacturer wants me to think about safety? For most things in your fridge, the answer is the second one. Your nose knows more than that date stamp does. Stay informed, stay curious, and we'll see you Monday.