Eggs last far longer than most people think. Here is how to check a questionable egg in under a minute, why the float test works, and which signs actually mean an egg has gone bad.
Lila Park
Fill a bowl or glass with cold water, deep enough to fully cover an egg. Gently lower the egg in. A fresh egg lies flat on its side at the bottom. An egg a few weeks old stands upright on its pointed end, still touching the bottom. An egg that floats to the surface is old enough that you should not eat it without further checking.
The test works because eggshells are porous. As an egg ages, moisture slowly evaporates through the shell and air takes its place, enlarging the air pocket at the wide end. More air means more buoyancy. Floating does not automatically mean rotten - it means old. But old eggs are the ones most likely to have gone bad, so a floater earns the crack-and-sniff check before it goes anywhere near a pan.
The only definitive test is to crack the egg into a separate bowl - never directly into your other ingredients - and smell it. A bad egg smells unmistakably sulfurous, like rotten cabbage or drains. You will not wonder whether it is off. If it smells like nothing, it is fine.
Look at it too. A fresh egg has a domed yolk and a white with two visible layers, a thicker inner ring and a thinner outer ring. An older egg has a flatter yolk and a runnier, spread-out white. That texture change is a quality issue, not a safety issue: older eggs are still fine for scrambles, baking, and hard-boiling, even if they are past their best for frying or poaching.
A sell-by or best-before date is a quality estimate, not a safety deadline. Properly refrigerated eggs are typically good for three to five weeks past the pack date, which is often weeks beyond the date printed on the carton.
In the US, look for the three-digit Julian pack date stamped near the sell-by date - 001 is January 1 and 365 is December 31. That tells you when the eggs were actually packed, which is more useful than the sell-by date for judging real age.
Keep eggs in their original carton on a middle shelf of the fridge, not in the door. The door is the warmest spot and gets a temperature swing every time it opens. The carton also stops eggs from absorbing odors from the fridge and keeps you from losing track of the pack date.
Store eggs pointed end down. The air pocket sits at the wide end, and keeping it on top slows the yolk's drift toward the shell, which helps eggs stay fresher for longer. If you bought unwashed eggs from a farm stand, they keep at room temperature for a week or two because the natural coating is intact - but once an egg has been refrigerated, keep it refrigerated.
A blood spot on the yolk looks alarming but is harmless - it is a ruptured blood vessel from when the egg formed, not a sign of fertilization or spoilage. Scoop it out with a spoon if it bothers you. Cloudy egg whites are actually a sign of freshness, caused by dissolved carbon dioxide that has not yet escaped through the shell.
The real red flags are a pink, green, or iridescent tint in the white (bacterial contamination), a black or green powdery interior (mold), or any sour or sulfur smell. Any of those means the egg goes in the bin, along with anything it touched.
Usually yes, if they have been refrigerated the whole time. Run the float test, then crack each egg into a separate bowl and smell it before using. Refrigerated eggs commonly stay good three to five weeks past the pack date.
No. Floating means the air pocket has grown, which means the egg is old. Many floaters are still fine. Crack it into a separate bowl and smell it - your nose gives the final answer, not the water.
Slight sulfur smell after long boiling is normal chemistry - heat releases hydrogen sulfide from the white. A bad egg smells foul when raw, before any cooking. If it smelled fine when cracked, it is fine boiled.
About one week in the fridge, in the shell. Peeled eggs dry out and pick up fridge smells faster, so peel them the day you eat them when you can.
