Related: Here are 7 foods that never expire. Like, ever.
States regulating date labeling: It's all over the place!
Want to know in part why this is so confusing?
Check out the excellent charts from Harvard Law Schools Food Law & Policy Clinic in partnership with other groups and published by ReFED (Rethink Food Waste) on state by state regulation of date labeling and more food safety processes and behaviors. It will help you at least be better informed as to whether the dates on your food are legally mandated or voluntary where you live, and help you make better decisions.
It also helps understand why this is so hard to understand! Only three states plus DC regulate "potentially hazardous foods." 7 states have no standardized regulations at all -- including New York. Yikes!
However we are happy to see that there's some strong, data-backed advocacy out there to change date stamps to two single stamps: "BEST if used by" to indicate product quality, and "USE by" to indicate product safety. Those two designations are cllearer to consumers (i.e. us), and will help us cut back on food waste and safe a lot of money throwing out those otherwise perfectly safe food items.
Click over to the entire PDF for even more specific information.
What does the "best by" date mean on packaged food?

What does the "use by" date mean on packaged food?
Surprisingly, the "use by" designation is basically the same as the "best by" designation—it's simply the date that the product will begin to lose peak flavor.
To be clear, "use by" is not a safety date.
If you're buying fresh or refrigerated food with a "use by" date, be aware that the the producer of that food item has determined that it will taste best by that date based on any number of factors specific to that particular food.
If you've stored it properly, the USDA says that it should be safe to eat after that date (with the exception of infant formula). But again, if it looks like it's spoiled, you're better safe than sorry. Avoid foods that have mold on them, smell off, or have an unusual color or texture to them.
Related:7 clever meat-free ways to get protein in your diet, now that we're living on rationed food!
What does the "sell by" date mean on packaged food?

A note about canned foods
There are dates printed in code on the bottom of your canned goods, but USDA specifies that these dates indicate the day an item was canned - and primarily used in case of a food recall.
If that weren't confusing enough, some canned goods also include a clearly marked "best by" date. That date does indicate a food item's best flavor and texture, though again, it is safe to eat it past that time as long as you don't see evidence of spoilage.
If you want a backup plan to check on potential food spoilage: Know that high-acid canned food (like tomatoes) are good for 12 to 18 months after canning, while low-acid foods like vegetables or canned meat can be eaten up to 5 years after the canning date.
However when a can is dented, rusted, or swollen (or of course if the food item smells off or looks spoiled) just toss it.
What about eggs? How long are eggs good?
You should know that most eggs arrive to the grocery just a few days after the hen lays them; the process is very fast.
Here's a tip for getting more info about the carton in your fridge right now: eggs with a USDA shield on them will have a three-digit code called a Julian date, which is printed on the package. The number ranges from 001 to 365. and it coordinates with the day of the year the eggs were packaged.
Don't worry, it's not a tough code to crack! My eggs (above) were packaged on day 066 -- the 66th day of the year -- which correlates with March 6, since this is a leap year.
The "sell by" date on eggs, according to the USDA, must be within 30 days packing. The United Egg Producers website states that eggs are safe to eat up to 3 weeks past this "best by/sell by" date, or up to 5 weeks past the Julian date, provided they're properly stored in the fridge or freezer.
(Yes, you can safely freeze eggs for up to 12 months according to Still Tasty.)
Personally, I'm more comfortable sticking with that Julian date. I noticed that my eggs were packaged on March 6 with a "best by" date six weeks later: April 19. If I go by the "3 weeks past the best by date" rule, I'd be waiting 9 full weeks to eat them from the time they were packaged. Now, in my house there's no chance a carton of eggs would last that long, but it's good to keep in mind.
Or, skip the dates and use this tried-and-true, easy way to test for the freshness of your egg: See if it sinks or float in a cup of water. If the egg sinks, it's still fresh. If it floats; it's not. This is because there's a tiny pocket of air inside the shell of a new egg, and it grows (and the egg becomes more bouyant) as the egg ages.



