The Science Behind the Float Test: Evaluating Egg Freshness

Eggs are a staple in many households, but have you ever wondered how to determine if an egg is fresh or not? One popular method used by home cooks and chefs alike is the float test. This simple yet effective technique involves placing an egg in a bowl of water to see if it sinks or floats. In this article, we will explore the science behind the float test and why it is a reliable way to evaluate egg freshness.

How Does the Float Test Work?

The float test relies on the principle of buoyancy. Fresh eggs have less air inside their shells, causing them to be denser and sink in water. On the other hand, older eggs tend to have more air inside, making them less dense and causing them to float.

Evaluating Egg Freshness

When an egg is laid, it has a protective coating called the bloom that helps seal its pores and prevent bacteria from entering. As time passes, this protective layer wears off, allowing more air to penetrate through the shell. This increase in air results in an older egg floating when placed in water.

It’s important to note that not all floating eggs are necessarily bad or rotten. Eggs that slightly tilt or stand on one end may still be safe for consumption but should be used soon. However, if an egg fully floats at the surface of the water, it indicates that it has gone bad and should be discarded.

Other Factors Affecting Egg Freshness

While the float test is a reliable method for evaluating egg freshness, there are other factors that can also influence an egg’s quality. For instance, proper storage plays a crucial role in maintaining freshness. Eggs should always be stored in their original carton at temperatures below 45°F (7°C) to slow down bacterial growth.

Additionally, handling can impact an egg’s freshness as well. Rough handling or dropping an egg can cause microfractures in the shell, increasing the risk of bacteria entering and spoiling the egg. Therefore, it’s essential to handle eggs with care to preserve their freshness.


The float test is a simple yet effective way to determine if an egg is fresh or not. By understanding the science behind this method, you can confidently evaluate the freshness of your eggs and make informed decisions when it comes to using them in your recipes. Remember to consider other factors such as storage and handling practices to ensure that your eggs remain fresh for as long as possible.

This text was generated using a large language model, and select text has been reviewed and moderated for purposes such as readability.