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How old are these store bought eggs?

We can all agree that raising our own chickens or buying from a local farmer is the best way to ensure freshly laid eggs. However, there may be occasions when buying from a supermarket is necessary. For those times, it is a good idea to know how to tell which eggs are the freshest and safest to eat.

The carton tells you more than you know

Egg cartons have several numbers on printed on them that may seem random or vague to the average consumer. Some egg cartons have no dates at all because they fall under the quantity limit requiring the labeling such as grade A or sell by dates.  We are talking about large commercial egg producers that are required to print information on the carton.  So what do the numbers mean?  Let's start at the beginning of your store egg's journey to better understand this topic. 

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The Full Story

According to, the US produced 96.9 BILLION eggs in 2020 from 325 million laying hens.  These hens will lay commercially for 18-80 weeks and then are sold into the meat industry.  It is important to understand the efficiency and precision by which large egg producers operate to better understand how it got to the grocery store.  The commercial egg producer is required to "package" the eggs into cartons within 30 days of the hen laying the egg.  The date on the carton known as the Packing Date or Julian Date.

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The Julian Date tells us all

We often focus on the Sell by or Expiration Date on our packages, paying little notice to the small 3 digit number on the carton.  However, the Julian date is far more informative than the sell by date.  In this picture, the Julian date is 221.  Beginning January 1st = 001 Julian date and ending with Dec 31st = 365 Julian date.  To get a general idea of when the eggs were packaged you can simply divide 221 by 30 = 7.36.  7th month = July so our date is somewhere between July & August.  If you wish to find the exact date, then there are handy Julian date tables online that will tell you the exact date represented by 221 Julian date which is August 9th. (leap years will vary)  Now look at the sell by date on this carton example, it is September 6th.  This is because stores are required to sell the eggs within 30 days of packaging date.  Again, not the day it was laid by the hen but the date that it was placed in the carton.


you may ask.  Well according to the USDA, refrigerated eggs are "good" for roughly 4-5 weeks after packaging. If you are purchasing eggs close to their sell by date, you have less than 1-2 weeks before they begin to significantly decline in freshness and become unsafe to eat.

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Ever wonder why your store bought eggs all look similar in size and color and shine?  Commercially produced eggs must be graded which means lesser quality eggs who do not meet the standards of Grade A will not get packaged but rather are turned into liquid products.  The store bought eggs are also sanitized chemically to ensure no bacteria or feces is left on the eggs prior to packaging.  Remember the cramped stressful conditions that these hens live their short lives and understand that stress can lead to contaminated eggs even though they are removed immediately after laying via mechanical "shoots" or conveyers.  To avoid any potential contamination liability, all store bought eggs are washed and polished prior to packaging.  
Unfortunately this also removes the protective barrier known as the BLOOM that nature provides the egg against such bacteria compromise.  To slow the spread of potential bacteria either introduced by the hen or environment, the USDA requires all eggs to remain refrigerated throughout their journey.  No more than 2 hours at room temperature are permitted in the whole process from hen to store.
Now let's break down the facts....

Let's compare

Farm vs Store vs Backyard

Store bought


  • 30 days to packaging

  • 30 days to sell after packaging

  • Trucked from producer to distribution center or directly to store. Consumer cannot visit farm directly

  • Must remain refrigerated with no more than 2 hours at room temperature for safety

  • 4-5 weeks lifespan from packaging date not sell by date

  • protective bloom compromise due to cleaning process

Local Farmer

Small scale

  • No packaging date required on carton if under quantity limit for exemption

  • Packaged 1-2 weeks from laying depending on size of flock

  • Delivered short distances by farmer or consumer.  Consumer has option to visit the farm directly.

  • Once refrigerated, eggs must remain refrigerated with no more than 2 hours at room temperature for safety. 

  • Unwashed fresh eggs can last 2 weeks unrefrigerated at room temperature and up to 3 months (12 weeks) in refrigerator.

  • protective bloom intact

Backyard Raised

Personal chickens

  • No packaging date required

  • No delivery time from hen to countertop

  • Option to keep unrefrigerated for 2 weeks from date of laying or refrigerate for 12 weeks of freshness from lay date.

  • Optional washing of egg shells.  Proper technique preserves bloom for longer shelf life

  • Satisfaction of knowing EXACTLY what ingredients went into that egg!

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