How to Tell If Eggs Are Still Good

You're standing at the fridge with an egg in your hand and no idea how old it is. Maybe the box is long gone, maybe you've lost track of the date. Don't worry, you can settle it in under a minute with things you already have. Here's how to tell whether an egg is still good, starting with the famous float test, and, just as importantly, what that test can and can't tell you.

The egg float test: fresh sinks, bad floats

This is the test grannies swear by, and it takes ten seconds. Fill a bowl or a deep glass with cold water and gently lower the egg in. A very fresh egg sinks and lies flat on its side on the bottom. As an egg ages it sinks but stands up on one end, tilted or pointing down. An egg that floats to the surface is old, so set it aside. Why it works: the shell is porous, so over the weeks a little moisture and carbon dioxide seep out and air seeps in, growing the pocket of air (the air cell) at the round end. The bigger that air pocket, the more the egg wants to float. So the float test is really an age test. It tells you how much air has built up inside, not whether the egg is safe. Keep reading, because a floater can still be perfectly fine and a sinker can still be off.

The shake test: hold it to your ear

If you'd rather not get a bowl out, hold the egg to your ear and give it a firm shake. A fresh egg is silent, or nearly so, because the white and yolk are plump and fill the shell, so nothing moves. An older egg sloshes, or you feel a faint slap inside, because the white has thinned and watered down and that air cell has grown. Like the float test, the shake tells you about age, not safety. A sloshy egg is past its best and better for hard-boiling or baking than for poaching, but it isn't necessarily bad. When in doubt, crack it.

The smell and crack test: the one that tells you it's off

This is the test that actually answers the question, is it safe? Crack the egg into a clean bowl on its own, never straight into your mixing bowl with everything else. A good egg smells of very little. A bad egg hits you with a sharp sulphur, rotten smell the moment the shell breaks. It is unmistakable, and it stays whiffy even after cooking, so trust your nose. Have a look, too. A cloudy white is a sign of freshness, not a fault (it is the carbon dioxide that hasn't escaped yet). A pink or red speck is just a harmless blood spot, so fish it out if you like, or ignore it. But a white or yolk that looks pink, green, or iridescent can mean spoilage bacteria, and a slimy or chalky shell is a bad sign, so throw those out. One honest caveat: neither the smell nor the look can spot salmonella, which is invisible and odourless. A fresh-smelling egg can still carry it, which is why the safe habit is to cook eggs until the white is set, and to keep them cold.

Age is not the same as safety

Here's the bit most guides skip. The float and shake tests measure age. The smell and crack test measures spoilage. They don't always agree. An egg can float because it is a few weeks old and full of air, yet crack open clean and cook up perfectly. Older eggs actually peel more easily once hard-boiled. And an egg can sink like a fresh one yet smell off when you crack it, if it was cracked, dirty, or badly stored. So use the tests in order: float or shake to judge age, then always crack into a bowl and smell before it goes anywhere near your cooking. When the two disagree, the nose wins. And the oldest kitchen rule holds: when in doubt, throw it out.

How long do eggs last? US fridge vs UK counter

In the US, eggs are washed before they're sold, which scrubs away the natural coating (the bloom, or cuticle) that seals the shell. Once that's gone the egg must be kept cold, so American eggs live in the fridge and keep for 3 to 5 weeks at or below 4C (40F), often a good while past the date stamped on the box, which is a best-before for quality, not a safety cliff. In the UK and much of Europe, eggs aren't washed, the cuticle stays intact, and they're traditionally kept somewhere cool at room temperature; they keep about 3 weeks, up to the best-before date (usually 28 days from lay). Whichever side you're on, keep eggs in their carton, not the fridge door, pointed end down, away from strong-smelling foods. And don't switch a fridge egg back to the counter. Once an egg has been chilled, condensation on a warm shell invites bacteria in, so keep it cold from then on.

Hard-boiled eggs, and the colours that are fine

Hard-boiled eggs keep up to 1 week in the fridge, whether still in the shell or peeled (store peeled ones in a covered tub, or in a little water changed daily). Don't leave them sitting out. Like any cooked food, cooked eggs shouldn't be in the danger zone of 4 to 60C (40 to 140F) for more than 2 hours, or 1 hour if the kitchen is above 32C (90F). A couple of colours look alarming but are harmless: a greenish-grey ring around the yolk is just a reaction between iron and sulphur from over-boiling (cook a touch less and cool fast in cold water to avoid it), and a slightly greenish or greyish yolk from the same cause is fine to eat. What isn't fine is any sour or sulphurous smell, or a slimy white. That's your cue to bin it.

Questions we get asked

What does it mean when an egg floats?

It means the egg is old, not automatically that it's bad. As an egg ages, air seeps through the porous shell and the air pocket inside grows until the egg becomes buoyant enough to float. A floater has simply lost moisture over time. Crack it into a bowl and smell it: if it smells fine and looks normal, it's usually still good for baking or hard-boiling. If it smells of sulphur, throw it out.

Are eggs that float always bad?

No. Floating shows age, not spoilage. Plenty of floaters crack open perfectly clean and cook up fine; in fact, slightly older eggs peel more easily when hard-boiled. The float test can't tell you an egg is off, only cracking and smelling can. When a floater smells rotten or looks pink, green, or slimy, then it's bad and should go in the bin.

Can you eat eggs past the best-before date?

Usually yes, if they've been stored properly. The date on the box is a best-before for quality, not a safety deadline. US eggs kept at or below 4C (40F) are commonly good for 3 to 5 weeks, often a bit past the printed date; UK eggs keep about 3 weeks. Always do the crack-and-smell check first, and cook them through to a firm white and yolk if you're eating them a while after the date.

How long do hard-boiled eggs last in the fridge?

Up to 1 week, in or out of the shell, kept at or below 4C (40F). Peeled ones do best in a covered container. Don't leave them out on the counter for more than 2 hours (1 hour if it's above 32C / 90F), and if a hard-boiled egg smells sulphurous or feels slimy, throw it out. The harmless green ring around the yolk is not a spoilage sign.

Should eggs be kept in the fridge or at room temperature?

It depends where you are. US eggs are washed, which removes the shell's natural seal, so they must be refrigerated and kept there. UK and European eggs are unwashed with the seal intact, so they're traditionally kept cool at room temperature. The one rule everywhere: once an egg has been chilled, keep it chilled. Moving a cold egg back to a warm counter causes condensation that lets bacteria in.

Can you freeze eggs?

Yes, but never whole in the shell, as they expand and crack. Beat whole eggs and freeze them for up to 1 year, or freeze the whites on their own (they freeze beautifully). Yolks alone tend to go gluey, so whisk in a pinch of salt or sugar first and label which you've used. Thaw frozen egg in the fridge and use it in cooking or baking rather than for a fresh boiled or poached egg.

Recipes that use it

• Old-Fashioned Deviled Eggs
• Old-Fashioned Pickled Eggs
• Old-Fashioned Egg Custard Pie
• Old-Fashioned Bread Pudding