Guide

Use By vs Best By vs Sell By — What the Labels Actually Mean

Three little phrases decide whether you eat the yogurt or bin it — and two of the three aren't even talking to you. Here's what the labels actually mean, according to the USDA, and when to ignore them.

You've probably stood at the fridge door, jar in hand, reading a date and wondering if eating this is a mistake. Most people guess wrong — and they usually guess wrong in the expensive direction. Confusion over date labels is one of the biggest drivers of household food waste: a Harvard Food Law and Policy Clinic / NRDC report found more than 80% of Americans throw food away early because of label confusion. The USDA estimates 30–40% of the US food supply is wasted, and the average household's share of that is about $1,500 a year — much of it food that was perfectly fine.

The one fact that changes everything

Here it is: except for infant formula, printed dates on food are not federally required, and almost none of them are about safety. The USDA's Food Safety and Inspection Service (FSIS) says it plainly in its food product dating guidance — dates on most foods indicate quality, not safety. Manufacturers print them to tell you when a product will taste its best, and stores use some of them to rotate stock. No federal rule forces a bag of chips or a carton of milk to carry a date at all (a handful of states have their own patchwork rules).

That doesn't make the dates useless. It means you need to know which label is speaking to you — and which one is speaking to the grocery store.

"Best by" is about taste, not safety

"Best if used by" (and its cousins "best by" and "enjoy by") is the most common label — and the most misread. The USDA's official position is that a food showing a "best if used by" date should still be safe, wholesome, and of good quality past that date, as long as it has been handled and stored properly. The date marks peak flavor, texture, and nutrition — not a cliff edge.

In practice: dry pasta, rice, canned beans, cereal, and crackers are fine for weeks to months past their best-by dates. Canned goods are the extreme case — USDA FoodKeeper guidance puts properly stored canned vegetables at two to five years, while the can's own date usually assumes far less. That date is the manufacturer's quality promise, not a countdown. As long as the can isn't bulging, deeply dented, or leaking, the contents are very likely fine.

What a best-by date can't tell you is how the food was stored. Flour that lived next to the oven, or nuts that spent a summer in a warm pantry, can go stale or rancid before their date. Trust your senses — rancid fat smells like old crayons, and you'll know it when you meet it.

"Sell by" isn't talking to you

The sell-by date is for the store. It tells retailers how long to display a product for inventory management. FSIS explicitly notes it's not a safety date for the consumer — by design, the product should outlive its sell-by date in your kitchen.

Milk is the classic example. Kept properly refrigerated at or below 40°F (not in the door, where temperatures swing), milk stays good for days past its sell-by date. Eggs are even more forgiving: USDA guidance says refrigerated eggs remain good for three to five weeks past the sell-by date on the carton. We break the egg math down in full — float test included — in our how long eggs last guide.

So if you've been pouring milk down the sink on its sell-by date, you've been funding the waste statistics. The date that deserves real caution is the next one.

"Use by" — the one to take seriously

"Use by" is the closest thing to a real deadline on a package. Per the USDA, it's the last date the manufacturer recommends using the product at peak quality — and for highly perishable foods like fresh meat, poultry, ready-to-eat deli items, and soft cheeses, treat it as a hard limit, not a suggestion.

The safety logic: "use by" dates on perishables assume the cold chain held — the product was kept cold all the way to your fridge. If it was, you have a grace window measured in days, not weeks. If it sat in a hot car for two hours, the date is worthless. If you know you won't eat something in time, freeze it before the date — freezing stops the clock. USDA guidance is blunt on this point: food kept frozen at 0°F stays safe indefinitely; only quality declines. Our freezer storage guide has the per-food timelines.

Use your senses alongside the date. Off smells, slime, visible mold, or a bulging lid are verdicts no date can overrule. But note the flip side: listeria and some other pathogens don't announce themselves by smell, so with ready-to-eat deli items and unpasteurized soft cheeses, when in doubt, throw it out. We build software, not food safety rules — the USDA's FoodKeeper app and FSIS guidance are the authority, and nothing here overrides them.

The one exception: infant formula

Infant formula is the single food where the date is federal law. The FDA requires "use by" dates on formula, and they mean exactly what they say: past that date, the nutrient content is no longer guaranteed, and the formula can separate or clump in ways that matter for feeding. Never use formula past its use-by date, and don't buy it on discount near the date. Of everything in the aisle, this is the one label that's a genuine safety-and-nutrition boundary — the law, and common sense, both agree here.

What about "packed on," Julian codes, and random numbers?

Some packages carry a "closed" code instead of a readable date — strings like "J245" or "L2107." These are manufacturer packing codes (the number is often the day of the year the item was packed), used for traceability. The USDA calls this "closed dating" and tells consumers not to read it as an expiration date. If a can has a code but no calendar date, use storage-time guidance — like FoodKeeper's timelines — as your clock, not the code.

The cheat sheet

Label decoder — meaning and realistic safe-to-eat window

Label	Who it's for	What it means	Realistic window if stored properly
Sell by	The store	Stock rotation deadline	Days to weeks past (milk: days; eggs: 3–5 weeks refrigerated)
Best by / Best if used by	You	Peak quality, not safety	Weeks to months past; canned goods 2–5 years
Use by	You	Last date for peak quality; treat as a hard deadline on perishables	Days at most — or freeze before it
Freeze by	You	Last date to freeze at peak quality	Safe indefinitely once frozen at 0°F (quality fades slowly)
Use by (infant formula)	You — required by law	FDA-mandated nutrient and safety guarantee	None. Never use past the date
Julian / pack code	Manufacturer	Traceability code, not a freshness date	Not a deadline; use storage guidance instead

Why this matters in money

Label confusion is expensive. The average US household wastes roughly $1,500 a year on food, and the most commonly trashed categories — dairy, produce, leftovers — are exactly the ones where people misread dates most aggressively. If "thrown out early because of the label" were a line item on your budget, it might be the easiest one to cut. We walk the full numbers in food waste statistics.

What an app does with all this

Knowing the rules is half the problem. The other half is remembering which label each of the forty things in your fridge is on — and acting before the deadline. That's the job ShelfLife automates: you snap one photo of your grocery receipt, AI reads every item in about three seconds — no typing — and each product gets an expiry estimate built from a multi-provider AI cascade with automatic failover, backed by caching and a USDA-derived offline fallback, so dates still arrive even with no signal. Alerts come at 7, 3, and 1 day out, urgent items ping within the hour, and Eat This First ranks what to cook tonight by urgency, recipe match, and value.

The USDA's own free FoodKeeper app is a solid reference for storage timelines — we compare the two honestly in ShelfLife vs FoodKeeper — but it's a database you look things up in, not a live inventory of your kitchen. ShelfLife's free tier covers 25 items with unlimited receipt scanning. Pro is $1.99/week, $6.99/month, or $14.99/quarter (best value) — unlimited items, unlimited receipt-scan saves, full AI expiry estimates on anything, household sharing with unlimited members.

For the deeper mechanics — how estimates work and how storage zones adjust them — see the complete guide to food expiry tracking and how AI estimates expiry dates.