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What do the Codes on an Egg Carton Mean?

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Whether you want to be sure you're choosing the freshest eggs, the most local eggs, or just want to understand the words and numbers on an egg carton, here's how to "crack the codes".

The tops of egg cartons read like veritable billboards these days. Shouting things like "Free-Range",  "Vegetarian", "Hormone-free" and "Farm Fresh". Unfortunately most of these terms are misleading at best and meaningless at worst. 

Most of you probably check the top of the egg carton for those key words that mean something to you, whether that be "organic" or "brown eggs" (although, spoiler alert, there's literally no difference in nutritional value between brown and white eggs). 


But, unfortunately, so much of what's printed on egg cartons is merely marketing terms or "feel good" words to compel you to buy those eggs instead of another brand. 

Hormones by law can't be given to laying hens, and antibiotics are rarely used.

I broke down exactly what "free range", "cage free", "pasture raised" and other egg carton terms mean here in this post.  (Tip: if you care at all about the way the hens that laid the eggs you're buying were treated, choose Certified Humane Pasture Raised eggs.)

But did you know that there are a few codes on each egg carton that can help you not only choose the freshest eggs, but also those that have traveled the shortest distance to get to you?

Today, I want to focus on some of the other codes on an egg carton and share how to read them and what they mean.


What do the Codes on an Egg Carton Mean?

1. Pack Date on an Egg Carton

In the past, I have  "cracked the code" on egg cartons, sharing how to read the 3-digit code that indicates when the eggs were put in the carton so you can tell how fresh the eggs are that you're buying. 

Basically, what you're looking for is the 3- digit number on the end of each egg carton. That is the Julian date, i.e. 001 is January 1st and 365 is December 31st, and that's the date the eggs were packed in the carton. 

So, for example, these eggs in the carton pictured below were packed on the 238th day of the year, which is August 26th. Here is a handy chart that lists the Julian dates for the entire year. 

Generally, you are going to want to look for the carton with the highest Julian date, which means the eggs are packed the closest to the date you're buying them and are therefore the freshest.


According to the USDA, refrigerated eggs can be safely used 4 to 5 weeks past the pack date, which brings us to the next set of numbers on an egg carton.

2. Best By, Sell by, Expiration or Use By Date on an Egg Carton


Different brands of eggs use different terminology, but there will always be a best by, sell by, expiration or use by date on the end of an egg carton. 

The date is not a federal requirement, except for egg producers displaying the USDA logo, but instead regulations vary by state.

That date is written out in an easily recognizable format.

Sell by Date or Expiration Date

The Sell by or Expiration date is mainly for the store use, letting them know when to pull that carton from the shelf if it hasn't sold. On cartons with the USDA logo, the expiration date can not be more than 30 days past the pack date. 

You should not purchase a carton of eggs past its sell by or expiration date, however eggs can still be used for several weeks past that date.

Best by or Use by Date

Conversely, a Best by or Use by date is primarily for the consumer's use and will generally be around 5 weeks after the Julian or pack date. 

In this case, you can see in the photo above that the Best by date is October 9th. 

The Best by or Use by date is the date until which the eggs should retain their freshness and quality. 

After that date, the whites will start to thin out, the interior lose moisture and dry out and the yolk membrane thin and be more apt to break when you crack the egg.

Which brings me to the next code on an egg carton.

3. Egg Grade on an Egg Carton


Eggs are graded into three different grades based on exterior and interior quality and freshness. Egg grading is voluntary and not required on egg cartons. 

Some producers choose to pay for the USDA Grade symbol which assures the quality of the eggs you're buying, while others do not. 


As you can see, the eggs in the carton pictures above are Grade A.

Eggs sold commercially are graded into three different grades:

  • Grade AA | these are the freshest and highest quality eggs, with an air pocket of less than 1/8 inch and whites that are thick and firm.
  • Grade A | these are the next highest-quality eggs, with reasonably firm whites.
  • Grade B | these eggs are usually used for commercial baking or liquid, frozen and dried egg products.
According to the USDA,  the grade of an egg is determined by the freshness and interior quality of the egg, and the appearance and condition of the egg shell.  

Both A and AA eggs are fine for everyday cooking and baking, with AA eggs having a slight edge when freshness really matters like if you're whipping egg whites or poaching or frying eggs. 

4. Egg Size on an Egg Carton


The egg size is also on each egg carton. Egg sizes range from peewee to jumbo.  

Egg cartons are weighed in total, not the eggs individually, so each individual egg might not weigh exactly the same, but instead the entire dozen will average out to the following guidelines: 

  • Peewee Eggs | an average of 1.25 ounces per egg
  • Small Eggs | an average of 1.5 ounces per egg
  • Medium Eggs | an average of 1.75 ounces per egg
  • Large Eggs | an average of 2.0 ounces per egg
  • Extra-Large Eggs | an average of 2.25 ounces per egg
  • Jumbo Eggs | an average of 2.50 ounces per egg

Large eggs are what are called for in most recipes and the most common size eggs sold in grocery stores.

5. Plant Code on an Egg Carton

The last set of numbers on an egg carton refers to the plant code where the eggs were actually packed into the cartons. 

The plant code is a four-digit number usually starting with the letter P. You can type the number (without the P) into this handy chart from the USDA to find out where the eggs you've bought were packed.


In this case, my eggs were packed in Gettysburg, Pennsylvania, which is just over 600 miles from my house. Not exactly "local", but could be worse! 

Using the USDA chart, though, I located an egg packaging plant just 79 miles from my house, and by finding cartons with the codes P2101 or P2105 at the grocery store next time, I can easily choose more local eggs.


I hope that you've enjoyed "cracking the code" on an egg carton with me and will use your new-found skills the next time you're at the grocery store buying eggs when your no-good, lazy, slacking chickens go on their next winter laying strike!  

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