Many shoppers have had that moment in the grocery store—picking up a carton of eggs and noticing a string of unfamiliar numbers printed on the package. Alongside the usual date, there might be a three-digit number, a letter followed by digits, and other markings that seem confusing at first. Are they expiration dates, store codes, or something else?

In reality, these small numbers contain useful information. Once you understand them, choosing a fresh carton becomes much easier and far less uncertain.

One of the most important markings is the Julian date. This three-digit number represents the day of the year when the eggs were packed. It starts at 001 for January 1 and goes up to 365 for December 31. By comparing this number on different cartons, you can quickly tell which eggs are fresher.

Another marking you may notice is the plant code. This usually appears as a letter—often “P”—followed by a series of numbers. It identifies the facility where the eggs were processed and packed. While most shoppers won’t need this detail, it becomes important for tracking in case of food safety concerns.

Cartons also include calendar dates, which can sometimes be misleading. A “sell by” date is mainly intended for stores to manage inventory. It does not mean the eggs are unsafe immediately after that date. When kept properly refrigerated, eggs can remain good for some time beyond it.

Proper storage is key to maintaining freshness. Experts recommend keeping eggs in their original carton inside the refrigerator. The carton helps protect them, reduces moisture loss, and prevents them from absorbing strong odors from other foods.

It’s also best to avoid washing eggs before storing them. Eggs naturally have a protective outer coating that seals their shells. Washing can remove this layer and shorten their shelf life.

When you’re ready to use eggs, there are simple ways to check their freshness. One common method is the water test: place an egg in a bowl of cold water. Fresh eggs will sink and lie flat, while older ones may stand upright or float due to air buildup inside the shell.

You can also crack the egg into a separate bowl before cooking. A fresh egg will have a firm yolk and a thick white that stays close together. If there’s an unusual smell or appearance, it’s safer not to use it.

Fresh eggs make a noticeable difference in cooking, especially in recipes where they play a major role. They provide better texture and consistency, whether you’re baking, scrambling, or preparing breakfast dishes.

Understanding egg carton labels doesn’t require any special knowledge. The Julian date tells you when the eggs were packed, the plant code shows where they came from, and the printed dates guide quality and storage decisions. The next time you’re shopping, those numbers won’t be confusing—they’ll be a simple tool to help you choose wisely.