Can I eat an egg that floats in water?

A floating egg is very old and should be discarded. The float test indicates a large air cell, which means the egg has lost a lot of moisture and is likely past its prime. Even if it doesn't smell bad, the quality will be poor, and the risk of spoilage is higher.

How long do eggs last in the refrigerator?

Fresh eggs in the shell, kept continuously refrigerated at 40°F (4°C) or below, are safe to eat for 3 to 5 weeks from the pack date. The sell-by date is a quality guide, not a safety cutoff. Always check for cracks and use the sensory tests if you're unsure.

Is the float test 100% accurate?

No. The float test reliably indicates age, but it cannot detect bacteria like Salmonella. An egg that sinks can still be contaminated. Use the float test together with the sniff test and visual inspection, and always cook eggs thoroughly.

What does a green ring around a hard-boiled yolk mean?

A greenish or gray ring on the yolk of a hard-boiled egg is caused by overcooking, which creates iron sulfide. It is harmless and does not indicate spoilage. To avoid it, cool the eggs quickly after boiling.

How to Tell If Eggs Are Still Fresh: The Float Test and Sensory Checks

Why the Float Test Works: Understanding the Air Cell

The float test is the most widely known way to check egg freshness, and it works because of a natural change inside the shell. As an egg ages, moisture and carbon dioxide escape through the porous shell, and the air cell at the blunt end grows larger. A fresh egg has a tiny air cell, so it sinks and lies flat on the bottom of a bowl of water. An older egg has a bigger air cell, making it tilt upward or float entirely.

This method is a reliable indicator of age, but it does not tell you whether the egg is safe to eat. A floating egg is not necessarily spoiled; it may simply be old. Conversely, a sinking egg is not a guarantee of safety if it has been stored improperly or cracked. Treat the float test as one part of a broader freshness check, not a standalone verdict.

For the test, place the egg gently into a deep bowl or glass of cold water. Do not drop it from a height, as the shell can crack and allow bacteria inside. Observe the egg's position: flat on the bottom means very fresh, standing upright on the bottom means older but likely still usable, and floating at the surface means it is past its prime and should be checked with other senses before use.

Egg lies flat on the bottom: very fresh, ideal for poaching or any use.
Egg stands upright on the bottom: a few weeks old, still fine for baking or scrambling.
Egg floats to the surface: old, likely not fresh; discard unless you prefer to crack it open for a sensory check first.

Three eggs in a bowl of water, one floating, one standing upright, one lying flat

Crack It Open: The Sniff Test and Visual Inspection

The sniff test is the most direct way to detect spoilage. Crack the egg onto a clean plate or into a small bowl, and smell it immediately. A fresh egg has little to no odor. A spoiled egg will have a distinct, unpleasant sulfur smell that is hard to miss. If you notice any off-putting aroma, discard the egg and wash the plate or bowl thoroughly before using it for anything else.

Look at the egg white and yolk. Fresh egg whites are thick and cloudy, with a firm yolk that stands tall. As an egg ages, the white becomes thinner and more watery, spreading out on the plate, and the yolk flattens and may break more easily. These changes are natural and do not mean the egg is unsafe, but they affect how the egg performs in cooking—older whites are less stable for meringues, for example.

Check for any discoloration or unusual spots. A fresh yolk is a vibrant yellow or orange, and the white is clear or slightly milky. If you see a greenish or gray ring around the yolk, that is usually a sign of overcooking, not spoilage. However, any pink, green, or iridescent sheen in the white indicates bacterial growth, and the egg should be thrown away.

Smell: no odor or very faint smell is normal; strong sulfur or ammonia means discard.
White: thick and cloudy is fresh; thin and watery is older but safe.
Yolk: high and round is fresh; flat and wide is older but safe.
Color: any pink, green, or iridescent tint in the white means discard.

Shake and Listen: The Slosh Test

A simple shake can give you a rough idea of an egg's age. Hold the egg close to your ear and shake it gently. A fresh egg feels solid inside, and you should hear little to no movement. An older egg has more liquid inside and a larger air cell, so you may hear a faint sloshing or feel a slight shift. This test is less precise than the float test, but it is useful when you cannot use water, such as when you are at a market.

The slosh test is not a reliable indicator of spoilage. A sloshy egg is simply older, and it may still be perfectly safe to eat if it passes the sniff test. Conversely, a fresh-feeling egg can still be contaminated with bacteria like Salmonella, which do not change the sound or feel. Use the shake test as a quick screening tool, not a safety check.

If you shake an egg and hear a distinct liquid movement, plan to use it soon, ideally in a recipe where texture matters less, like a baked casserole. For recipes that rely on the egg's structure, such as soufflés or custards, choose eggs that feel solid when shaken.

Check the Date and Storage Conditions

The pack date, printed as a three-digit number representing the day of the year (January 1 is 001, December 31 is 365), tells you when the eggs were washed and packed. The sell-by date is a quality guideline, not a safety deadline. Eggs are typically safe to eat for 3 to 5 weeks after the pack date, even if the sell-by date has passed, provided they have been refrigerated continuously.

Storage conditions matter as much as the date. Eggs should be kept in the refrigerator at or below 40°F (4°C), in their original carton on a shelf, not in the door where temperatures fluctuate. If eggs have been left at room temperature for more than two hours, discard them, as condensation can form and allow bacteria to enter through the shell.

Cracked eggs are a food safety risk. Even a hairline crack can let bacteria in, so discard any egg with a visible crack or leak. Also, avoid using eggs that are past their prime for raw or lightly cooked preparations like homemade mayonnaise or soft-poached eggs, even if they pass the float test.

Date label	What it means	How to use it
Pack date (Julian)	Day eggs were washed and packed	Use as the starting point for the 3–5 week freshness window
Sell-by date	Last day the store should sell them	Eggs are usually still safe for 1–2 weeks after this date if refrigerated
Best-by date	Quality estimate, not a safety date	Eggs may still be fine beyond this date if they pass sensory checks

Putting It All Together: A Practical Freshness Checklist

To decide whether an egg is fresh enough to use, run through these checks in order. First, look at the shell: it should be clean, dry, and free of cracks. Second, do the float test to gauge age. Third, crack the egg into a separate bowl and smell it. Fourth, inspect the white and yolk for color and texture. If the egg passes all of these, it is safe to use, though you may want to adjust your cooking method based on its age.

A fresh egg (flat on the bottom, thick white, high yolk) is best for frying, poaching, or any dish where appearance matters. An older but still good egg (upright on the bottom, thinner white, flatter yolk) works well for scrambling, baking, or hard-boiling, where the texture is less noticeable. An egg that floats or smells bad should be discarded, and the container it touched should be washed with hot, soapy water.

Remember that freshness and safety are not the same thing. Even a very fresh egg can carry Salmonella if it was contaminated before the shell formed. Always cook eggs until the white and yolk are firm, and avoid raw or undercooked eggs for young children, pregnant women, older adults, and anyone with a weakened immune system.

Shell: clean, dry, no cracks—discard if cracked or visibly soiled.
Float test: flat on bottom = fresh; upright = use soon; floating = discard or verify by smell.
Sniff test: no odor = good; sulfur smell = discard.
Visual: white clear, yolk round and bright; any pink/green/iridescent = discard.
Date: within 3–5 weeks of pack date and refrigerated = likely safe.
Cook thoroughly: always cook eggs until white and yolk are firm.