Lower the egg into a bowl of cold water and watch what it does. Then tell the tool where it came from and how it has been kept. You get the honest answer, including the part every other page leaves out: floating shows how old an egg is, not whether it is safe.
Floating shows how old an egg is, not whether it is safe — USDA’s own words, below.
Your egg
Fresh — use it
How long it keeps — every official answer
Cook eggs until the yolk and white are firm. If an egg smells bad or looks wrong when you open it, it goes in the bin whatever the water said.
Egg safety sources checked 2026-09-22.
Quick answer: put the egg in a bowl of cold water. If it sinks and lies flat, it is fresh. If it sinks but stands up on its point, it is older and best hard-boiled. If it floats, it is old — but the USDA’s own words are that a floating egg “may be perfectly safe to use”: crack it into a separate bowl and throw it away only if it smells or looks wrong. And the part nobody says: a sinking egg is not a safe egg either. The water measures age, not bacteria.
How to do the float test properly
Use cold tap water in a bowl or a tall glass, deep enough to cover the egg with room to spare. Lower the egg in gently rather than dropping it, and give it a few seconds to settle. Look at the broad end — that is where the air pocket sits, and it is the air pocket you are really looking at.
Test your doubtful eggs and then dry them and use them soon. Water on a shell is not something you want sitting in the fridge, and an egg you have wetted has lost some of whatever protection its coating gave it.
What the water is actually measuring
A new-laid egg has almost no air cell. As it cools, a small pocket forms at the broad end between the two membranes under the shell, and as the days go by water and carbon dioxide slip out through the shell’s pores and that pocket grows. A bigger pocket means a lighter egg, and a light enough egg tilts, then stands, then floats.
It is the same thing the USDA measures when it grades eggs, just done in a bowl instead of against a candling light. An egg only stays Grade AA while its air cell is an eighth of an inch deep or less, Grade A up to three-sixteenths, and anything deeper is Grade B. The EU uses millimetres — 6 mm for Class A, 4 mm for eggs sold as “extra”. None of those grades is a safety grade. They are about how an egg looks, stands up in the pan and holds its shape.
Why a floating egg is not automatically bad
This is the sentence almost every float-test page gets wrong, so here it is in the USDA’s own words: “An egg can float in water when its air cell has enlarged sufficiently to keep it buoyant. This means the egg is of poor quality, but it may be perfectly safe to use. Crack the egg into a bowl and examine it for an off-odor or unusual appearance before deciding to use or discard it.”
A spoiled egg tells you itself — you will know the smell the moment the shell breaks. So crack a doubtful egg into a small bowl on its own, never straight into a cake mix with three good ones, and let your nose decide.
The reverse matters more. Salmonella does not make an egg float, and an egg that sinks beautifully can still carry it. That is why the advice for eating eggs never changes: cook them until the white and yolk are firm, and cook dishes with eggs in them to 160 °F.
How long eggs keep — and why the official answers disagree
Ask three official sources and you get three answers, a couple of months apart:
- USDA FSIS says raw eggs in the shell keep 3 to 5 weeks in the fridge.
- The University of Arizona Extension, writing for backyard keepers, says unwashed eggs in a carton keep up to 2 to 3 months in a household fridge.
- Penn State Extension says home-flock eggs can be stored safely for at least one month if they are covered.
They are not really contradicting each other. The USDA figure covers the washed eggs sold in every American store; the Arizona figure is for unwashed eggs straight from your own hens, which still have their natural coating — the bloom, or cuticle — sealing the pores of the shell. The checker above shows every figure and highlights the ones that apply to your egg, rather than picking one and pretending the others do not exist.
Counter or fridge? What the rules actually say
You will read that “Europeans keep eggs on the counter”, and that is only half true. EU rules forbid washing the eggs sold as Class A and forbid chilling them below 5 °C before they are sold, which is why supermarkets there keep eggs on an ordinary shelf. But the same regulation requires the box to tell you to keep them chilled after you buy them, and caps the best-before date at 28 days after laying.
In the US, the USDA, Penn State and the University of Arizona all say the same thing: refrigerate eggs as soon as you can. No US agency publishes a safe time for eggs on the counter, so this tool does not invent one. And once an egg has been in the fridge, it has to stay cold: the USDA’s rule is that a refrigerated egg should not be left out for more than 2 hours, because a cold egg sweats at room temperature and that moisture helps bacteria through the shell.
To wash or not to wash
If an egg is clean, leave it alone. The USDA does not recommend washing eggs at home, because wash water can be drawn into the egg through the pores, and the University of Arizona points out that washing removes the bloom. If one needs cleaning, Penn State’s rule is specific: one egg at a time, agitated rather than soaked, in water with a food-safe detergent at least 20 °F warmer than the egg and never below 90 °F — and then into the fridge. An egg that stays dirty after a dry brush, or one that is cracked or leaking, goes in the bin.
Eggs from a hidden nest
Every keeper finds one eventually: a clutch behind the feed bin, under the ramp, in the long grass. The float test cannot date it, because the hen laid those eggs days apart and a fresh one can be sitting next to a three-week-old one. Collect what you find, crack each egg into its own bowl, and judge them one at a time. If a broody hen has been sitting on the clutch, some eggs may have started to develop — another reason to open them away from anything you want to eat. And the lesson is the boring one: collect once or twice a day, every day. I wrote more about it in how long eggs can stay in the coop.