Fill a glass with water. Drop the egg in. That is the entire test.

I learned this from a neighbor who raised chickens in her backyard in Austin. Before that, I did what most people do — I looked at the date on the carton and hoped for the best. The problem is that sell-by dates on eggs are not expiration dates. Eggs can be perfectly good two or even three weeks past the date stamped on the carton. And eggs can go bad before that date if they were stored wrong at some point between the farm and your fridge.

The float test takes five seconds and has not failed me once.

How the Float Test Works

Eggshells are porous. Over time, moisture and carbon dioxide escape through those pores and air replaces them. An older egg has more air inside, which makes it more buoyant.

• Sinks to the bottom and lays flat on its side: Very fresh. Perfect for poaching or frying where you want the yolk to hold its shape.
• Sinks but stands upright on the bottom: Still fine to eat. A week or two old. Use these for hard boiling — slightly older eggs peel more easily.
• Floats to the surface: Toss it. The egg has enough air inside to float, which means it is old and likely spoiled.

What About the Smell Test

If an egg passes the float test but you still feel uncertain, crack it into a separate bowl before adding it to your pan. A bad egg announces itself immediately — the sulfur smell is unmistakable. But honestly, after doing the float test for years, I have never had a floater that smelled fine or a sinker that was secretly bad.

Other Signs of Freshness

When you crack a fresh egg into a pan, the white will be thick and stay close to the yolk. An older egg has a thin, watery white that spreads out across the pan. Not unsafe — just less pretty.

The yolk should be domed and bright yellow or orange. A flat, pale yolk means the egg has been sitting around a while. The color depends mostly on the hen’s diet, not freshness, but the shape tells you something.

I also shake eggs near my ear sometimes. A fresh egg makes almost no sound. An older egg sloshes because the contents have shrunk away from the shell. This is not as reliable as the float test, but it works in a pinch if you do not have a glass of water handy.

Why It Matters

Americans throw away something like two hundred million eggs a year, many of them still perfectly good, because we rely on carton dates that do not actually measure safety. The float test is free, takes seconds, and has kept me from wasting dozens of eggs.