An egg that floats in plain water is usually old and much less fresh, and many food safety sources recommend treating it as suspect or discarding it.

Quick Scoop

  • An egg floats because its shell is porous and, over time, it loses water and gains air, enlarging the internal air cell and reducing the egg’s overall density.
  • When the air cell gets large enough, the egg becomes buoyant and will stand upright or float in a bowl of water, which is a sign of age, not a precise “pass/fail” for safety.
  • Many egg safety groups note that a floating egg is generally older and may still be safe, but common kitchen advice is to crack it into a separate bowl and rely on sight and especially smell; any off odor means you should throw it away.

How The Water Test Works

  • Fresh eggs typically sink and lie flat on the bottom because they are denser than water and have a small air cell.
  • As the egg ages, water inside slowly evaporates through microscopic pores in the shell while air and decomposition gases can enter, making the egg lighter for the same volume.
  • Once enough mass has been lost, the egg will first tilt upright and eventually float, which signals that it is old and more likely to be spoiled than a sinking egg.

Does Floating Always Mean “Bad”?

  • Some producers and safety organizations emphasize that floating means “older, not necessarily rotten,” because an egg can be buoyant before it is actually spoiled.
  • Other cooking guides frame the test more strictly and say a floating egg should be considered rotten and discarded, since age correlates with bacterial growth and quality loss.
  • In practice, food safety educators suggest combining tests: check if it floats, then crack it into a clean bowl and use a sniff test and visual inspection to decide whether to use it.

What To Do If Your Egg Floats

  1. Place the egg in a bowl of cool tap water and confirm it is really floating, not just standing upright.
  1. If it floats, treat it as old: crack it into a separate bowl rather than directly into a recipe.
  1. Look for signs like a very runny, watery white, discolored yolk, or any unusual appearance, and discard it if anything seems off.
  1. Smell the egg; a sulfurous, “rotten egg” odor is a clear sign it is unsafe and must be thrown away.

When in doubt, especially with a floating egg, the safest choice is to throw it away rather than risk foodborne illness.

Information gathered from public forums or data available on the internet and portrayed here.