Simply fill a bowl with cold tap water and place your eggs in it. If they sink to the bottom and lay flat on one side, they are fresh and good to eat. A bad egg will float because of the large air cell that forms at its base. Any floating eggs should be thrown out.

Does rotten egg really float?

If the egg sinks, it is fresh. If it tilts upwards or even floats, it is old. This is because as an egg ages, the small air pocket inside it grows larger as water is released and replaced by air. ... An egg can sink and still be bad, while an egg that floats may still be fine to eat (3).

Do rotten eggs float or sink in water?

The float test does not determine whether an egg has gone bad, but it does provide a useful indication of the age of an egg. To perform the float test, place the egg in a large bowl of water. If the egg sinks or stays at the bottom, it is still fresh. An older egg will either stand on its end or float.