Expiration Dates: What 'Best By' Actually Means

Flip over almost any package of food and you’ll see a date stamped on it. Most people treat that date like a deadline. Throw it out if you’re past it. The reality is messier, more interesting, and actually useful to know.

Date labels on food packaging are largely unregulated, inconsistently applied, and routinely misunderstood. That misunderstanding costs Americans real money and generates enormous amounts of wasted food.

What the Different Labels Actually Mean

There are four main types of date labels on food. They mean very different things, but they don’t look different on the package. The label just reads a date.

Sell by is an inventory management signal aimed at retailers, not consumers. It tells store staff when to pull a product from the shelf so newer stock can rotate in. A gallon of milk with a sell-by date of February 20 is still safe to drink for several days after that, assuming it’s been properly refrigerated.

Best by (also written as “best if used by”) indicates peak quality. After this date, the manufacturer can’t guarantee the food will taste or perform the way they intended. The product doesn’t become dangerous. A bag of crackers two weeks past its best-by date will taste a little stale. It won’t make you sick.

Use by is the closest thing we have to a safety date, and even then it’s only meaningful on perishable products. Manufacturers set this date based on testing of their specific product. For deli meat, fresh pasta, or refrigerated juice, a use-by date is worth respecting.

Pack date is simply the date the product was processed or packaged. You’ll see this most often on fresh meat in grocery store cases. It’s not a safety cutoff. It’s a freshness reference point.

The critical fact: only infant formula has mandatory date labeling under US federal law. The FDA requires use-by dates on infant formula because nutritional integrity is a genuine safety concern for infants who depend on it entirely. For everything else, date labels are voluntary, and there’s no standardized definition. One company’s “best by” might be another’s “sell by.” The same phrase can mean different things on different packages.

What Actually Makes Food Unsafe

Food safety is a microbiology problem, not a calendar problem. Harmful bacteria like Salmonella, Listeria, and E. coli don’t read labels. They grow when conditions are right: the right temperature range, enough moisture, and enough time.

Think of it like a petri dish. You can have a perfectly safe piece of chicken on day 8 and a dangerous one on day 3, depending entirely on how each was handled and stored. The temperature danger zone (40°F to 140°F / 4°C to 60°C) is where bacterial growth happens fastest. A product stored in a warmer refrigerator, or left on a counter, becomes unsafe faster than the date on the package assumes. Learn more about how temperature affects bacterial growth in our guide to the temperature danger zone.

The other factor is the product’s intrinsic properties. Water activity (a measure of available moisture), pH, salt content, and preservatives all affect how hospitable a food is to microbial growth.

Foods That Are Safe Long Past Their Date

Some foods have properties that make them essentially shelf-stable indefinitely.

Honey is the classic example. Honey is hygroscopic (it draws moisture away from its surroundings), high in sugar, low in water activity, and slightly acidic. These properties make it nearly impossible for bacteria to grow in it. Archaeologists have found 3,000-year-old honey in Egyptian tombs that was still safe to eat. The “best by” date on a jar of honey is a quality indicator for color and texture, not a safety cutoff.

Salt and white sugar don’t support microbial growth because they have essentially zero water activity in their pure forms. They can clump or absorb odors, but they don’t go bad in any meaningful safety sense.

Distilled spirits with high alcohol content (vodka, rum, whiskey) don’t spoil. Alcohol at sufficient concentration is antimicrobial. A bottle of whiskey opened a decade ago is still safe to drink.

Commercially canned goods are heat-sterilized and sealed in an oxygen-free environment. If the can is intact, not swollen, not corroding, and doesn’t have off odors or appearance when opened, the contents are safe to eat years past any printed date. The USDA notes quality degradation over years but no safety concern with intact cans.

Foods Where Dates Matter More

The flip side of that list is the category of foods where you should take dates seriously.

Deli meat and hot dogs are in a genuinely higher-risk category. They can harbor Listeria monocytogenes, a pathogen unusual for its ability to grow slowly even in refrigeration. Listeria is particularly dangerous for pregnant women and immunocompromised people. Use-by dates on these products reflect real safety testing.

Soft cheeses (ricotta, brie, fresh mozzarella, cottage cheese) have high moisture content that supports pathogen growth. Hard cheeses like aged parmesan or cheddar have much lower moisture and are more forgiving.

Eggs have USDA pack dates and recommended use-by windows. A simple float test tells you more than a date: fresh eggs sink flat, older eggs tilt up, bad eggs float (gas produced by bacterial activity makes them buoyant).

Fresh poultry and ground meat degrade quickly due to high surface area and moisture. Take the date seriously and freeze if you can’t use within a day or two.

How to Actually Assess Food Safety

Use your senses. They evolved partly for this purpose.

Smell is your most reliable tool. Spoilage bacteria produce compounds that smell wrong. Sour, putrid, or “off” smells are your nose detecting those metabolic byproducts. Trust it.

Visual inspection catches mold, sliminess, and unusual discoloration. Sliminess on meat or produce is a biofilm, a sign of heavy bacterial colonization. See our guide to mold on food to understand exactly when you can cut away mold and when you should toss the whole thing.

Texture matters for some products. Milk that has gone sour will be visibly clumped. Bread that’s stale vs. bread with actual mold is a different safety situation.

The exception to the “use your senses” rule is the category of pathogens that don’t produce detectable changes in food. Salmonella and E. coli O157:H7, for example, can be present in dangerous numbers in food that looks, smells, and tastes completely normal. For those pathogens, proper sourcing, cooking temperature, and handling matter far more than any label date.

A Practical Framework

Use this mental model: Is this a shelf-stable product or a perishable one?

Shelf-stable products (canned goods, pasta, rice, crackers, honey, vinegar, salt, sugar, spirits) can generally be assessed by condition, not date. Damaged packaging, rust, or off odors on opening are red flags. A printed date is not.

Perishable products (meat, dairy, eggs, fresh produce, deli items) warrant more attention to dates, and more attention to storage conditions. A perishable stored at the correct temperature is safer than one that’s been temperature-abused, regardless of what the label says.

The calendar date on a package is one data point. It’s not the most important one.