How To Tell An Egg Is Bad? Your Complete Beginner Guide

A spoiled egg usually announces itself the moment you crack it open. The smell is unmistakable — sulfurous, rotten, sometimes faintly like a swamp. If you are holding an egg and wondering whether it is still good, you have three reliable checks: the float test, your nose, and your eyes. None of them require special equipment. All of them work because a rotting egg changes physically long before you would ever want to eat it.

Here is the short version. A fresh egg sinks in water and lies flat on its side. A bad egg floats. A fresh egg smells like almost nothing when raw and has a clean, mild smell when cooked. A bad egg smells rotten, sour, or like sulfur. A fresh egg white is thick and stays close to the yolk. A bad egg white is thin, watery, and may be discolored.

This guide walks through each test, explains why it works, and covers the situations where the usual rules do not apply — like cracked shells, old cartons, and eggs you find in the back of the fridge.

How To Tell An Egg Is Bad: The Float Test Explained

The float test is the most well-known home method, and it works for a simple physical reason. An eggshell is porous. Over time, moisture inside the egg evaporates through the shell and air seeps in to replace it. The air pocket at the wide end of the egg — called the air cell — grows larger as the egg ages.

Fill a bowl with cold water and gently lower the egg in.

• Sinks and lies flat on its side: Very fresh.
• Sinks but stands upright on one end: Older, but usually still fine to eat.
• Floats to the surface: The air cell has grown large enough to make the egg buoyant. This is a strong sign the egg is old and likely spoiled.

One important clarification. Floating does not prove an egg is contaminated with bacteria. It proves the egg has lost enough moisture and gained enough air to become buoyant, which takes time. Age and spoilage usually travel together, but they are not the same thing. A floating egg should be discarded because the odds are bad, not because floating itself is proof of bacteria.

Similarly, an egg that sinks is not automatically safe. The float test tells you about age. It does not detect every kind of spoilage. That is why you should always follow it with the smell and sight checks.

What Does a Bad Egg Smell Like?

Smell is the single most reliable home test. A spoiled egg produces hydrogen sulfide and other compounds as bacteria break down the proteins inside. That is the source of the classic rotten-egg odor.

Crack the egg into a separate bowl — never directly into your pan or into a batch of other ingredients. If a strong, unpleasant smell hits you, throw the egg out and wash the bowl thoroughly with hot soapy water before using it again.

What you are smelling for:

• Rotten or sulfurous: Spoiled. Discard.
• Sour or sharp: Spoiled. Discard.
• Faintly sulfurous when cooked: This is different. Overcooked eggs can develop a mild sulfur smell and a greenish ring around the yolk. That is a cooking reaction, not spoilage.
• Nothing much at all: Normal for a fresh raw egg.

A fresh raw egg has very little odor. If you have to lean in and think hard about whether it smells off, it is probably fine — but if you are unsure, the safe move is to discard it. The cost of one egg is not worth a bout of foodborne illness.

How To Tell If an Egg Is Bad by Looking at It

Your eyes catch things your nose might miss. Crack the egg into a clean bowl and look at the white and the yolk separately.

The egg white (albumen). In a fresh egg, the white is thick and holds its shape around the yolk. In an older egg, the white becomes thin and watery and spreads out across the bowl. Thin white alone does not mean the egg is spoiled — it means the egg is older. But thin, watery white combined with an off smell or a discolored yolk is a clear sign to discard.

The yolk. A fresh yolk is round, firm, and stands up slightly. An older yolk flattens and is easier to break. A yolk that is discolored — greenish, blackish, or with visible patches — should be discarded. Pink, green, or iridescent discoloration in the white can indicate Pseudomonas bacteria, which is a genuine spoilage concern. Do not eat it.

Blood spots. Small blood spots or meat spots in an egg are not spoilage. They occur when a tiny blood vessel ruptures during the egg’s formation. They are safe to eat. You can remove them with the tip of a knife if they bother you.

Cloudiness. A cloudy egg white is actually a sign of freshness. It comes from carbon dioxide still dissolved in the white. As the egg ages, the carbon dioxide escapes and the white becomes clearer. So cloudy is good, not bad.

Does the Sell-By Date Tell You If an Egg Is Bad?

No, and this trips people up constantly. The sell-by date on an egg carton is not an expiration date. It is the last day the store should sell the eggs. It says nothing about when the eggs will actually go bad.

Refrigerated eggs generally stay safe to eat for several weeks past the sell-by date. The exact window depends on how the eggs were handled, how cold your fridge runs, and how consistent that temperature has been. Rather than rely on the date, rely on the tests above. If the egg sinks, smells clean, and looks normal, it is almost certainly fine.

One caveat. This applies to eggs stored in the refrigerator. In the United States, commercial eggs are washed before sale, which removes the natural protective coating on the shell. That is why US eggs need refrigeration. In many other countries, eggs are not washed and are often stored at room temperature. The storage rules are different, and so is the timeline. Follow the storage guidance where you bought the eggs.

Can You Tell If an Egg Is Bad Before Cracking It?

Only partially. Before you crack an egg, you have two useful signals: the float test and the shell itself.

A shell that looks or feels unusual deserves attention. Watch for:

• Cracks or chips: Even a hairline crack lets bacteria in. Cracked eggs should be discarded unless you cook and eat them immediately and thoroughly.
• A powdery or moldy appearance: Discard.
• A slimy or unusually shiny shell: Discard.
• A leaking egg: Discard.

What you cannot do is smell or see inside an intact egg. The float test is your best pre-crack check, but it only measures age, not contamination. Once the shell is broken, your nose and eyes take over.

What About Cracked Eggs and Raw Egg Safety?

A clean, uncracked egg is remarkably well protected. The shell and inner membranes keep bacteria out. Once that barrier is broken — by a crack, a chip, or a careless crack into the pan — bacteria like Salmonella can move in.

The CDC advises against eating raw or lightly cooked eggs, especially for people who are pregnant, young children, adults over 65, and anyone with a weakened immune system. Cooking eggs until both the white and yolk are firm kills Salmonella. Dishes that use raw or undercooked eggs — homemade mayonnaise, some Caesar dressings, certain mousses, and raw cookie dough — carry a real risk.

If you handle raw eggs, wash your hands, the bowl, the counter, and any utensils with hot soapy water. Do not let raw egg touch other foods. And if an egg smells bad at any point during preparation, stop. Throw it out and clean everything it touched.

When in Doubt, Throw It Out

There is no clever trick that beats this rule. If an egg fails the float test, smells off, or looks wrong, discard it. If it passes all three checks, it is very likely fine to eat.

The three checks work together. The float test measures age. Your nose detects spoilage compounds. Your eyes catch discoloration and texture changes. No single test is perfect on its own. Used together, they give you a reliable answer almost every time.