Food Expiration Dates Explained: Sell By, Use By, and Best By

Roughly 80 percent of Americans discard food prematurely because they misread date labels — a finding documented by the Natural Resources Defense Council and Harvard Food Law and Policy Clinic in their landmark 2013 report, The Dating Game. The three labels printed on nearly every packaged food in the United States — "Sell By," "Use By," and "Best By" (or "Best If Used By") — mean different things, carry different legal weights, and send different signals about safety versus quality. Getting them confused costs the average American household an estimated $1,500 per year in wasted food (USDA Economic Research Service). Knowing what each label actually means is one of the simplest ways to reduce that waste without compromising food safety.

Definition and scope

The foundational confusion is this: only one of these three labels has anything to do with safety in the clinical sense, and it applies to a narrow category of foods.

Sell By is a retailer-facing inventory management tool. It tells the store how long to display a product — it is not a safety cutoff for the consumer. A gallon of milk labeled "Sell By June 10" may remain safe to consume for 5 to 7 days after that date if stored at or below 40°F (FDA Food Code).

Best By (also labeled "Best If Used By" or "Best Before") signals peak quality — flavor, texture, aroma. It is a manufacturer's promise about palatability, not a warning about pathogen growth. Crackers past their "Best By" date may taste stale; they are unlikely to make anyone sick.

Use By is the most serious of the three. The FDA recommends treating "Use By" as a hard deadline for perishable items — particularly infant formula, where the date is federally mandated under 21 CFR § 107.10. For other products, "Use By" indicates the manufacturer's assessment of the last date the product will be at peak safety and quality.

The scope of federal regulation here is narrower than most people assume. Outside of infant formula, the US has no federal law requiring manufacturers to print any expiration date on most food products. Date labeling requirements vary by state — at least 41 states have some form of date labeling law, but the standards and terminology differ substantially (USDA Food Safety and Inspection Service).

How it works

Manufacturers determine these dates through a combination of laboratory stability testing, sensory panel evaluation, and regulatory guidance. The process is not random, but it is also not standardized in the way a drug expiration date is.

A typical shelf-life study involves storing the product under controlled conditions — temperature, humidity, light exposure — and testing samples at intervals for microbial counts, pH changes, moisture activity, and sensory characteristics. The date printed on the label is often set conservatively, sometimes 20 to 30 percent before the point at which the product actually deteriorates, to account for variability in retail and home storage conditions.

The USDA's Food Safety and Inspection Service oversees date labeling for meat, poultry, and egg products. The FDA covers all other packaged foods. Neither agency pre-approves the dates manufacturers choose — the system is largely self-regulated, with post-market enforcement triggered by complaints or documented illness.

For a broader look at how food safety oversight is structured across federal agencies, the key dimensions and scopes of food safety page provides a useful orientation.

Common scenarios

The gap between what labels say and what they mean becomes most visible in everyday kitchen decisions.

  1. Milk, 3 days past "Sell By": Still safe if stored below 40°F and passing the smell test. Pasteurized milk's spoilage bacteria produce obvious off-odors before reaching dangerous concentrations.

  2. Deli meat, 2 days past "Use By": This is higher-risk territory. Deli meat is a known vehicle for Listeria monocytogenes, which grows at refrigerator temperatures. The USDA recommends consuming opened deli meat within 3 to 5 days regardless of the printed date (USDA FSIS Fact Sheet).

  3. Canned goods, 2 years past "Best By": Commercially canned foods with intact seals are typically safe indefinitely from a pathogen standpoint, though quality degrades over time. The USDA notes that high-acid canned goods (tomatoes, fruit) retain best quality for 12 to 18 months; low-acid canned goods (vegetables, meats) for 2 to 5 years.

  4. Infant formula, 1 day past "Use By": Do not use it. This is the one category where the "Use By" date is federally enforceable and non-negotiable — nutritional content cannot be guaranteed after that date.

  5. Eggs, 1 week past "Sell By": The USDA permits a 45-day period from the date of pack for shell eggs sold in the US. The Julian date on the carton — a 3-digit number from 001 (January 1) to 365 (December 31) — tells the actual pack date. Eggs are generally safe 3 to 5 weeks past purchase when refrigerated.

Decision boundaries

The question "is this still safe?" runs through two separate filters: pathogen risk and quality degradation. They are not the same thing, and conflating them is how both food waste and foodborne illness happen.

A useful framework for deciding whether to eat or discard:

  1. Identify the label type. "Use By" demands more caution than "Best By." "Sell By" is almost never relevant to the safety decision a consumer is making at home.

  2. Assess the food category. High-risk foods — deli meats, raw poultry, soft cheeses, cut leafy greens — warrant stricter adherence regardless of label language. These categories appear in greater detail on the high-risk foods for contamination page.

  3. Check storage conditions. A product stored at 45°F rather than 40°F degrades faster than its label anticipates. The food temperature danger zone defines the 40°F to 140°F range where bacterial growth accelerates most rapidly.

  4. Use sensory evaluation — carefully. For low-risk foods (dry goods, canned goods, hard cheeses), smell and visual inspection are reasonable secondary checks. For high-risk foods, sensory evaluation is insufficient: Salmonella, E. coli O157:H7, and Listeria are odorless and tasteless at dangerous concentrations.

  5. When in doubt about perishables, discard. The cost of a single case of foodborne illness — in medical expenses, lost work, and suffering — far exceeds the cost of a package of chicken. The foodborne illness symptoms and causes page documents what that illness can look like in practice.

The National Food Safety Authority home page provides orientation across all food safety topics, including recalls, handling practices, and regulatory oversight.

For safe storage practices that extend the useful life of food within its actual safety window, the safe food storage guidelines page covers temperature ranges, container types, and category-specific timelines.

References

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