Why Do Eggs Float?

When it comes to why some things float and others sink, density has a role to play. Things with a density greater than water sink, while lighter objects float.

Objects are constructed from millions of microscopic molecules. It is possible to pack molecules together in a rock-like fashion, or to spread them out like bubble wrap. The density of an object is influenced by the arrangement of its molecules. Denser objects have molecules that are compactly packed, whereas molecules that are dispersed are less dense.

The fact that air is less dense than water means that hollow objects can float as well. Large, heavy ships float in part because of this. One more consideration is the object’s overall shape. The more of an object’s surface that is in contact with water, the more buoyant it is. In order to float, water pushes back against objects, so larger objects have more surface area and therefore more water pushes back against them.

Eggs that have a lower density than water are able to float. However, what is it about the egg that makes it less dense than water? Let’s begin with gaining an understanding of an egg’s anatomy before moving on to the question of why eggs float in water.

Anatomy of the egg

There are eight distinct components that make up the egg itself: the shell, the yolk, the yolk membrane, the air cell, the chalazea, the albumen, the germinal disk, and the shell membrane. There is a specific function that each individual component of the egg fulfills.

Shell: The egg’s first line of defense against bacterial invasion is its shell, which includes roughly 10,000 small pores that allow moisture and gasses to enter and exit freely.

Air cell: Cooling of the egg causes an air cell to form at its widest point. Eggs that have been refrigerated for longer have a smaller air cell.

Albumen: Two-thirds of an egg’s weight is composed of albumen. Water, high-quality protein, and minerals make up the bulk of the thick and thin albumen layers.

Yolk membrane: The yolk membrane (vitelline membrane) encircles and protects the yolk, which is contained inside it. The stronger the yolk membrane is, the fresher the egg.

Yolk: The yolk, which makes up one-third of an egg’s weight, is the primary source of the egg’s vitamins and nutrients. A hen’s nutrition can affect the color of her yolks, which can range from light yellow to dark orange.

Chalazea: There are two spiral bands in the albumen that hold the yolk in place. The chalazea is more evident in eggs that are still warm.

Germinal disk: As a tiny indentation on the surface of the yolk, the germinal disk is an access point for fertilization.

Shell membrane: The egg’s second line of protection against bacteria is its shell membrane, which is made up of two membranes: one that adheres to the shell and the other that surrounds the albumen.

Reasons why eggs float

Eggshells may appear to be quite solid, but closer inspection reveals that they have a few microscopic pores.

Eggs are equipped with a buoyancy aid in the form of an air cell that, as the egg develops, expands and becomes larger. When an egg’s air cell has grown to the point where it can maintain its buoyancy even when submerged in water, the egg is able to float.

Eggs that have been laid for a long time develop a large air cell after being laid, which allows them to float in water that is both fresh and cold. As the egg matures, air is drawn into it, and the air cell within the egg grows larger; this has the effect of making the egg more buoyant.

Eggs that are older have a tendency to tilt so that the larger end is facing upward. The eggs are able to tilt because of air pockets within them. These air pockets grow larger over time due to the evaporation of fluid through the porous shell and the infiltration of oxygen and gases. The longer an egg is stored, the greater the amount of gas that develops inside of it. More gas in the pockets means more floating!

The water that is contained within an egg’s shell will eventually evaporate as the egg ages, and it will be replaced by air or any gases that are produced as the egg rots. When spoiled, a wide variety of food products—vegetables, fruits, animals, and the like—give off gases, which frequently have an unpleasant odor. When eggs go bad, they produce a smell that is so distinctive and foul that we use the phrase “smelling like rotten eggs” to describe the odor. In any case, as the egg ages, it ends up having more gas inside of it and less water, and since gas is lighter than water, the egg ends up being lighter overall. Overall, this makes the egg lighter, and in fact, it becomes less dense than water, which causes the egg to become less dense than water and float.

Be aware that fresh eggs will float in saltwater since the density of saltwater is greater than that of the eggs. Salt dissolved in water increases the density of the solution.

Floating egg – good or bad

A basin of water with fresh eggs in it will usually have them sink to the bottom.

It’s possible you’ve noticed that some eggs float in fresh water while others don’t and have wondered what this indicates for egg quality. While it’s commonly believed that a floating egg indicates a bad egg and should be discarded, this isn’t always the case.

Eggs that float have the potential to be harmful. Check for a foul odor, a sure sign that it has deteriorated, by breaking open the container.

Fresh eggs sink in a basin.

You can still eat an egg even if it is slanted on the bottom. You can eat it, but it’s better for baking and preparing hard-cooked eggs if its pointed end is at the bottom. Do the final test if the egg floats.

Finally, the ultimate test:

Break the egg into a clean basin and inspect it for an unpleasant odor or appearance to ensure it is not ruined.


The egg float test simply reveals an egg’s age, not its safety. When an egg’s air cell expands enough, it floats. This signifies the egg is aged yet still edible. Before using or discarding the egg, crack it into a basin and smell it. Raw or cooked, rotten eggs have an awful odor when cracked.

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