Things You'll Need
Wide-mouth glass jar
Chicken eggs you buy at the grocery store come with an expiration date on the carton that makes it easy for a consumer to know when the eggs should be used or discarded. People who raise backyard chickens might have a harder time gauging the freshness of their chicken eggs. Knowing the freshness helps you avoid possible food-borne illnesses. Fresher eggs taste better too. Luckily, chicken eggs don't go bad very fast, but it's better to test the freshness of eggs when you aren't sure of the date they were laid.
Fill a wide-mouth, glass jar with about six inches of cold water.
Set the egg in the water-filled jar and then look at the egg from the side of the jar.
Note the angle of the egg. A fresh egg will sit horizontally on the bottom of the jar. The big end of a one-week-old egg will rise slightly. As the egg ages, the air pocket inside enlarges due to evaporation. This causes the rising of the big end of the egg. The larger the air pocket the older the egg. The older the egg the higher up the big end will rise. A two-to-three week old egg will stand vertically on the bottom of the jar. The big end will be touching the bottom and the small end will be pointing upward. When an egg floats, its freshness has greatly diminished.
Smell any floating eggs and if you smell a foul sulfur-like smell, the egg is rotten. Toss it.
The cold water makes the pores in the egg shell contract. Cold water makes it harder for bacteria to enter the egg while these pores are contracted. Keeping eggs in a fridge keeps them fresher longer, because the cold temperature minimizes bacterial growth. Mark the gathering date on the shell of each egg you collect to help keep track of freshness. If you gather them every day, you'll know that they were also laid on that day. Use a pencil to mark the date.
Avoid using hot water to run these tests or the egg shell will expand and the pores will be more prone to allowing bacteria to enter the egg.