You reach into the fridge, pull out an egg, and realize the carton has no date you can trust. Maybe it fell off, maybe you transferred the eggs to a bowl, or maybe you just can’t remember when you bought them. The good news is that eggs tell you a lot about themselves if you know what to look for. The float test, the smell test, and the crack-and-look method can each give you useful information, and none of them requires special equipment.
How To Test Eggs For Freshness
The most reliable at-home test is the float test, also called the water test. Place the egg in a bowl of cold water. A fresh egg sinks and lies flat on the bottom. An older egg sinks but stands upright on one end. An egg that floats to the surface is old enough that you should not eat it.
The reason this works comes down to the shell. An eggshell is porous, and over time the liquid inside slowly evaporates through those tiny holes. As the liquid level drops, the air pocket at the wide end of the egg grows larger. More air means more buoyancy. A floating egg has lost enough moisture that its air cell is big enough to lift it off the bottom.
A few practical notes. Use cold water, not hot, because hot water can affect the shell. And handle the egg gently. If it floats, don’t crack it open to check — just discard it.
The float test has limits. It tells you about the age of the egg roughly, but it doesn’t detect bacteria like Salmonella. An egg can sink and still be contaminated. The float test is a freshness gauge, not a safety test.
What Does the Smell Test Tell You About an Egg?
A spoiled egg has a distinct, unpleasant sulfur smell. If you crack an egg and it smells rotten or like sulfur, throw it out. That smell comes from hydrogen sulfide gas produced by bacteria breaking down the egg’s contents.
Here’s the catch: you have to crack the egg to smell it. So the smell test only works after you’ve already committed to opening it. A fresh egg has almost no smell. A slightly older but still safe egg might have a faint odor, but nothing strong or offensive.
If the smell is bad, don’t taste it to confirm. Just discard it and wash your hands and any surfaces the raw egg touched.
Does a Bad Egg Always Look Bad When You Crack It?
Not always, but appearance gives you useful clues. When you crack a fresh egg into a bowl, the yolk sits up high and round, and the white is thick and stays close to the yolk. As an egg ages, the white becomes thinner and spreads out more. The yolk also flattens.
These changes happen because the egg’s internal structure breaks down over time. The thick white proteins that hold the yolk in place gradually thin out. That’s why older eggs spread wider in the pan.
Look for these signs that an egg should be discarded:
- A pink, greenish, or iridescent discoloration of the white or yolk
- A cloudy, runny white that spreads very thin and far
- A yolk that breaks easily and looks flat or watery
- Any visible mold or dark spots
- A strong unpleasant odor
A cloudy white is actually normal for a very fresh egg. The cloudiness comes from carbon dioxide dissolved in the white, and it fades as the egg ages. So cloudy is good, not bad.
A small blood spot or meat spot on the yolk is also normal and not a sign of spoilage. These are tiny bits of tissue that can appear during egg formation. They are safe to eat, though some people prefer to remove them.
How Long Do Eggs Stay Fresh?
Refrigerated eggs keep their quality for about three to five weeks from the date you bring them home. That’s a general guideline, not a hard rule. The actual shelf life depends on how the eggs were handled before you bought them and how consistently they stay cold.
Eggs bought at a store in the US are typically washed and refrigerated, which removes the natural protective coating on the shell called the bloom. Once that coating is gone, the egg is more vulnerable to moisture loss and bacterial entry. That’s why US eggs need refrigeration.
In some countries, eggs are sold unwashed and stored at room temperature. Those eggs keep longer without refrigeration because the bloom is intact. This is a real difference in how eggs are processed, not a difference in the eggs themselves.
If you’re not sure how old your eggs are, the float test gives you a rough idea. But it won’t tell you the exact age. It just tells you whether the egg is likely still good or likely past its prime.
Can You Eat an Egg That Floats?
No. An egg that floats in water should be discarded. The float test is not a perfect safety test, but floating is a clear sign that the egg has lost a significant amount of moisture and its air cell has grown large. At that point, the risk of bacterial contamination is higher, and the quality is poor.
Some people argue that a floating egg is still safe if it doesn’t smell bad when cracked. That’s risky advice. The absence of a bad smell doesn’t guarantee the egg is free of harmful bacteria. Salmonella can be present without any obvious signs.
When in doubt, throw it out. The cost of one egg is not worth a foodborne illness.
Why Do Some Eggs Float Sooner Than Others?
How quickly an egg floats depends on how it was stored and handled. Temperature changes are a big factor. If eggs go from cold to warm and back to cold, condensation can form on the shell, which can help bacteria move through the pores. That speeds up spoilage.
Humidity also matters. In a dry environment, eggs lose moisture faster. In a humid environment, they lose it more slowly. That’s why eggs stored in a humid refrigerator compartment tend to stay fresh longer than eggs left on a dry counter.
Handling matters too. Cracked eggs spoil faster because bacteria have a direct path inside. Even a hairline crack you can barely see can let in air and microorganisms. Always check eggs for cracks before you buy them, and discard any that are cracked.
Here’s a non-obvious point: the float test measures air cell size, not bacterial load. An egg can have a large air cell and still be free of harmful bacteria, or a small air cell and be contaminated. The test is a freshness indicator, not a safety guarantee. That’s why you should combine it with the smell test and a visual check when you crack the egg.
What About the Shake Test?
Some people shake an egg near their ear to listen for sloshing. A fresh egg doesn’t slosh much because the inside is thick and fills the shell. An older egg sloshes because the white has thinned and the air cell is larger.
The shake test is less reliable than the float test. It’s hard to hear the difference, and the results are subjective. If you’re going to use one test, use the float test. It’s more consistent and easier to interpret.
How Should You Store Eggs to Keep Them Fresh?
Keep eggs in their original carton in the coldest part of your refrigerator, not in the door. The door is the warmest part because it’s opened and closed frequently. The main compartment stays colder and more consistent.
Leave eggs in the carton. The carton protects them from odors and helps maintain a stable temperature. It also has the date on it, which helps you track how long they’ve been there.
Don’t wash eggs before storing them. If they’re already washed (as most US eggs are), washing again removes nothing useful and can push bacteria through the shell. If you have unwashed eggs, leave them unwashed until you’re ready to use them.
If you need to store eggs long-term, you can freeze them. Crack them, beat them lightly, and freeze in an airtight container. Frozen eggs keep for up to a year, though the texture changes and they’re best used in cooked dishes rather than for frying or boiling.
When Should You Not Rely on Home Tests?
Home tests are useful for judging freshness, but they don’t detect all types of contamination. If you’re cooking for someone who is pregnant, elderly, very young, or immunocompromised, be extra cautious. Those groups are at higher risk for serious illness from foodborne bacteria.
If an egg has been left out at room temperature for more than two hours, discard it. That’s a standard food safety guideline. Bacteria can multiply quickly at room temperature, and no home test can reliably detect that.
If you’re ever unsure, the safest choice is to throw the egg away. No test is perfect, and the consequences of eating a bad egg can be serious.
Frequently Asked Questions
How do I test eggs for freshness?
Place the egg in a bowl of cold water. If it sinks and lies flat, it’s fresh; if it stands upright, it’s older but usually still safe; if it floats, discard it.
Can I eat an egg that floats?
No. A floating egg has lost enough moisture that its air cell is large, which means it’s old and potentially unsafe. Throw it away.
Does a cloudy egg white mean the egg is bad?
No. A cloudy white is actually a sign of freshness. The cloudiness comes from carbon dioxide dissolved in the white, and it fades as the egg ages.
How long are eggs good after the sell-by date?
Refrigerated eggs generally keep for about three to five weeks from the date you bring them home. The sell-by date is a guide, not a deadline, but always check for signs of spoilage.
