How long fresh chicken eggs remain safe to eat is a common question for home cooks. When stored correctly in a refrigerator, eggs maintain their quality and safety for a long period. The cold temperature significantly slows the growth of bacteria and the natural degradation process. Understanding the difference between an egg’s quality and its safety is the first step in maximizing its use.
The Standard Shelf Life
Eggs typically remain safe for three to five weeks when kept consistently refrigerated, according to U.S. Department of Agriculture (USDA) guidelines. This timeframe begins from the date of purchase, not the date they were laid. Refrigeration is required for commercially produced eggs in the United States to maintain safety.
The “sell-by” or “expiration” date on the carton is a guideline for retailers to ensure peak quality, but it is not a strict safety deadline. Eggs often remain safe to consume for one to two weeks beyond that date, provided they are continuously stored in the cold. While quality, such as the firmness of the yolk and thickness of the white, diminishes over time, the egg remains safe.
The pack date, a three-digit Julian number, represents the day the eggs were washed and packaged, offering a precise measure of age. For optimal quality, use eggs within a few weeks of this date. Maintaining a consistent, cold environment is the primary factor in extending the shelf life to the full three to five weeks.
Factors That Affect Freshness
The location and temperature within the refrigerator significantly affect an egg’s freshness. Eggs should be stored in the main body of the refrigerator, such as on a middle shelf, rather than in the door. The door is the warmest section and experiences the most temperature fluctuations, accelerating the decline in quality.
Maintaining a consistent temperature below 40°F (4°C) inhibits bacterial growth and slows the aging process. Eggs should be kept in their original carton, which serves multiple protective functions. The carton shields the eggs from absorbing strong odors and flavors from other foods through the porous shell.
The shell of a fresh egg is naturally protected by a thin outer layer called the cuticle or “bloom.” In the United States, commercial eggs are washed, removing this protective layer. This washing makes the shell susceptible to bacterial penetration, requiring store-bought eggs to be refrigerated. Farm-fresh, unwashed eggs with the bloom intact can be stored at room temperature, but once refrigerated, they must remain cold.
Simple Tests for Spoilage
When the date on the carton is unclear or has passed, simple at-home tests can determine the egg’s condition. The float test assesses the size of the air cell inside the egg. As an egg ages, moisture evaporates through the porous shell, causing the air space at the wide end to grow larger and making the egg more buoyant.
To perform the test, gently place the egg in a glass of cold water. A fresh egg will sink and lie flat on its side. An older egg that is still safe will sink but stand upright on its pointed end. If the egg floats completely to the surface, it indicates a very large air cell and should be discarded.
The most reliable indicator of spoilage is the smell test, performed after cracking the egg. A spoiled egg emits an unmistakable, strong sulfurous or “rotten” odor, whether raw or cooked. If the egg smells unpleasant, it should be thrown out immediately. A final visual inspection may reveal a watery white or a flat yolk, which are signs of diminished quality. However, any pink, green, or iridescent discoloration indicates bacterial contamination and requires immediate discarding.