Carefully lower your eggs into fresh cold water using a spoon (you can do this in the pan if you're about to boil them). If the eggs stay at the bottom they're fresh; if the eggs float, however, they're stale and best avoided.
If they sink to the bottom and lay flat on one side, they are fresh and good to eat. A bad egg will float because of the large air cell that forms at its base. Any floating eggs should be thrown out.
The water test for egg freshness
Very fresh eggs will sink to the bottom and lay on their sides. If an egg stays at the bottom but stands on its small end, it's still acceptable to eat; just not quite as fresh.
If the eggs sink to the bottom and lay flat on their side, they're still fresh. However, if they sink, but stand on one end at the bottom of the glass or bowl, they're not as fresh but still edible. Of course, if any eggs float to the top, they shouldn't be eaten.
As long are they are kept refrigerated at 45 °F or lower, fresh shell eggs are safe to be consumed four to five weeks beyond the carton's Julian date (the date eggs were packed).
If they are less fresh but still good to eat, they will stand on one end at the bottom. If they float to the surface, they are no longer fresh enough to eat. This is because as the egg gets older, the size of the air sac inside increases, making it float.
Old eggs should always be disposed of responsibly to avoid contamination and food-borne illnesses. You can choose to compost, feed them to animals, recycle them at local centers, or throw them in the trash. Eggs with foul odors or discoloration may be spoiled and should not be eaten.
Float test
If it sinks or stays at the bottom, it is still fresh. An older egg will either stand on its end or float. The float test works because air builds up inside the egg as it ages, increasing its buoyancy.
You can eat eggs past their expiration date. Just be sure to keep your eggs egg-cellent by storing them correctly. If you don't know if an egg is good or not, you can try the float test or give it a whiff. If it doesn't pass the test, throw it away.
Hard-boiled eggs, peeled or unpeeled, are safe to eat up to seven days or one full week after they were cooked. To make sure they stay fresh, allow the cooked eggs cool a bit, and then store them in a sealed container in the refrigerator.
Fresh eggs can be kept refrigerated for up to 6 weeks but always check the use by date displayed on the carton. It is best to put eggs in the fridge as soon as you get them home.
Some egg cartons have sell-by dates on them, while others have expiration dates. Neither should be regarded as an indication of when the eggs are no longer safe to use. Both the Food and Drug Administration and Egg Safety Center agree that eggs are usually good for several weeks past the stamped date.
You can store fresh shell egs in their cartons in the the refrigerator for four to five weeks beyond this date. Plants not under USDA inspection are governed by the state laws where the eggs are packed and/or sold.
The Best Method for Uncracked Eggs: The Float Test
If they sink to the bottom and lay flat on their sides, they're very fresh. If they're a few weeks old but still good to eat, they'll stand on one end at the bottom of the bowl. If they float to the surface, they're no longer fresh enough to eat.
Eggs may be refrigerated three to five weeks from the day they are placed in the refrigerator. The "Sell-By" date will usually expire during that length of time, but the eggs will be perfectly safe to use. Always purchase eggs before the "Sell-By" or EXP (expiration) date on the carton.
Information. Bacteria can enter eggs through cracks in the shell. Never purchase cracked eggs. However, if eggs crack on the way home from the store, break them into a clean container, cover tightly, keep refrigerated, and use within two days.
Judging the freshness of your eggs
Semi-fresh eggs: Eggs which are semi-fresh should sink to the bottom but stand up straight. Older eggs: If your egg floats higher than halfway towards the surface of the water this means it's most definitely not fresh and consumption should be avoided.
Information. An egg can float in water when its air cell has enlarged sufficiently to keep it buoyant. This means the egg is old, but it may be perfectly safe to use. Crack the egg into a bowl and examine it for an off-odor or unusable appearance before deciding to use or discard it.
Salmonella is common in eggs, whether they are good or bad. However, salmonella is cooked out of eggs with heat. As eggs go bad, they develop other types of bacteria like E. Coli that lead to severe illness.
What happens if you use old eggs. If you use older eggs, the cakes will not rise as well and pavlovas will be flatter than they should be. Generally, the cakes will still work as long as you get some volume from beating, they just won't be as tall or light-as-air as they should be.
If it floats, throw it out. The smell test will only identify severely rotten eggs, while the float test will hint at how well the egg will perform as a binder in baking recipes.
Place your eggs in the water. If your eggs sink to the bottom and lie flat on their sides, they are very fresh. If your eggs stand on one end at the bottom, they are a few weeks old, but still fine to eat. If your eggs float to the surface, they are no longer fresh.