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USDA-based guidance

USDA-based · How this page was made · Last reviewed August 18, 2026 · Sources ↓

Sell by, best by, use by: what the date on the package really means

Almost every date on almost every package is the manufacturer's guess about flavor. Only one kind is a safety deadline, and it is probably not the one you think.

The fact that reframes all of this

With a single exception, US federal law does not require date labels on food at all. Manufacturers apply them voluntarily. There is no federal standard defining what "best by" means, no agency verifying the date is correct, and no legal prohibition on selling or eating food past it.

The exception is infant formula, which is federally regulated and where the date is a real deadline. We come back to that below, because it is the one place where the usual advice inverts.

Everything else is the manufacturer's own estimate of when their product stops being at its best. That estimate is usually conservative, because a company would rather you throw out a perfectly good yogurt than eat a mediocre one and think less of the brand. Their incentive and yours are not the same.

The phrases, one at a time

"Best if Used By" / "Best if Used Before"

A quality date, and the phrasing the USDA actually recommends manufacturers standardize on. It marks when the product is expected to have the best flavor and texture. It says nothing about safety. Crackers past this date go stale; they do not become dangerous.

"Sell-By"

This one is not addressed to you at all. It is an inventory instruction to the store, telling them how long to display the item. It is deliberately set to leave reasonable home storage life after purchase — often a week or more for refrigerated products.

Milk is the classic case. Milk bought a day before its sell-by date and kept at or below 40°F is typically fine for a week past it, sometimes longer. Our milk page gives the specific window.

"Use-By"

The phrase that causes the most confusion, because it sounds like a deadline and — outside of infant formula — is not one. On ordinary food it is the manufacturer's last date for peak quality, the same category as "best if used by".

That said, it is often applied to the most perishable products in the case, so it tends to appear on things that genuinely do not last long. Treat it as a strong hint about perishability rather than as a legal expiry.

"Freeze-By"

Tells you when to move something to the freezer to preserve quality. Not a safety date, and not a purchase or use deadline.

Closed or coded dates

The strings of numbers stamped on cans and shelf-stable boxes are usually packing codes for the manufacturer's own tracking — batch, plant, line. They are for recalls and inventory rotation, not for you. Canned goods generally keep for years past them; see our pantry entries.

The exception: infant formula

Infant formula is the one product where the date is a genuine safety and quality deadline that is federally required and enforced. Do not buy it, use it, or feed it past the "use by" date.

The reason is nutritional rather than bacterial: over time the formula can lose the nutrient levels declared on the label, and the fat can separate in ways that affect how it mixes and passes through a bottle nipple. For an infant on formula as a sole food source, degraded nutrition is a real harm. This is the one case where the printed date wins outright.

How to actually decide, then

If the date is not the answer, what is? Three things, in order:

Why this matters beyond your grocery bill

Date-label confusion is one of the larger single contributors to household food waste in the United States. People throw out sealed, perfectly safe food because a number printed for inventory purposes passed a few days earlier. The USDA and FDA have both pushed for standardizing on "Best if Used By" precisely because the current patchwork of phrases reads as a safety warning when it usually is not.

The practical upshot: use the date as one input, not as the verdict. Combine it with how long the thing has been open, how cold it has been kept, and what it looks like. That is what the storage windows on this site are for — they are built from time and temperature, which is what actually governs, rather than from a number a marketing department chose.

If you want the mechanism behind those windows, start with the danger zone. If you want to know whether your fridge is holding up its end, see fridge temperature.

Sources

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