Is the Egg Float Test a Myth?

• It's true that fresh eggs sink in water, while older ones float. However, an egg that floats can still be safe to eat.
• Eggs that are bad or rotten have a nasty smell and often look runny. Avoid using them as well as any eggs that were cracked in the carton.
• Store eggs in the refrigerator for 5 weeks, or 4-5 weeks past their packing date. Eggs can be frozen for up to 1 year.

Is the egg floating test accurate?

Partially—the egg floating test speaks to an egg’s age, not its quality. The famous “egg float test” simply involves filling a cup with water and submerging an egg. According to the popular myth, eggs that sink are fresh and safe to eat, while eggs that float are old and unsafe to eat. Only half of the myth is true; while a floating egg is definitely old, it is not necessarily bad or dangerous to eat. Instead, it’s best to examine the egg's physical qualities, like how it looks or smells when you crack it open. Anatomically speaking, all eggs have an air pocket that forms within the shell. Believe it or not, air can actually enter the egg through the shell; over time, this extra air increases the volume of the air pocket, which causes the egg to float when submerged in water. Some versions of the egg float test encourage cooks to look at the angle of the egg in addition to whether it’s floating or not. Eggs that sink horizontally to the bottom are completely safe, as well as eggs that sink and sit at an angle. Meanwhile, eggs that sit on the bottom with the pointy facing down are okay to eat but better for baked or hard-boiled recipes. Ultimately though, the best way to evaluate an egg is by cracking it open and looking at or smelling it. Warning: Cook the egg right away if you choose to use the float test. Once you soak the egg, it becomes more susceptible to bacteria.

Other Egg Freshness Tests

Avoid eating eggs that smell rotten. Like many perishable foods, eggs give off a distinct odor when they’re rotten and no longer safe to eat. If the egg smells pretty sulfuric when you crack it open, there’s a good chance that it’s off. Ideally, fresh eggs shouldn’t smell like much of anything. Exception: Eggs might smell foul if they’re stored right next to something especially pungent (like a leftovers dish containing cooked fish).

Don't use eggs with runny whites or yolks. When eggs start to go bad, the white and/or yolk may develop a runny consistency. The white may also take on a different color (like green or pink) when it’s contaminated with bacteria. An ideal, safe-to-eat egg has an orange- or yellow-hued yolk along with a white that’s translucent or slightly opaque.

Toss out eggs with cracked, slimy, or powdery shells. A crack in an eggshell is a free portal for bacteria to enter through and contaminate the egg; so, it’s never a good idea to cook with an egg that’s been cracked for an unknown amount of time. Slimy shells are also a red flag for bacteria, while powdery residue can be a sign of mold. Exception: If the egg crack just happened (e.g., you dropped it on the countertop), transfer the egg to an airtight container in the refrigerator for up to 48 hours or use it right away. If the egg seems perfectly fresh but has a slight bit of powder on top, it might just need to be rinsed off.

Bake or scramble eggs that move around inside the shell. Older eggs have less of a defined shape on the inside and are more likely to make a little noise when you shake them around. While this doesn’t necessarily mean they’re rotten, you’re better off using these eggs for a recipe that calls for scrambled or baked eggs.

Use eggs within 4-5 weeks of the pack date. To tell if eggs are still fresh, examine one of the short sides of an egg carton for the sell-by date and the 3-digit pack date. While the sell-by date can be a helpful reference, the pack date (underneath the sell-by date) gives you the clearest idea of when the eggs were placed in the carton. Aim to eat your eggs within around 4-5 weeks of this pack date. The pack date uses a Julian dating system, where all dates are numbered between 1 and 365/366. Simply Google “what is the [pack date number] day of the year” to figure out when your eggs were packed. The pack date is preceded by an alpha-numeric code that starts with P—this corresponds to the plant where the eggs were packaged up.

How to Keep Eggs Fresh

Store the eggs for 5 weeks in the back of the refrigerator. Keep your eggs inside their carton rather than storing them in a different way. Be sure not to stash them in the refrigerator door, since they’ll be exposed to a lot of temperature changes there. Eggs are good to use for about 5 weeks in the fridge. However, counting 4-5 weeks past the packing date is also a good rule of thumb to follow.

Freeze the eggs for up to 1 year. Crack the eggs if you’d like to preserve them and whisk them together; for every 4-5 eggs that you use, stir in ½ tsp (3 g) of salt, 1 ⁄2 US tbsp (22 mL) of corn syrup, or 1½ tbsp of sugar (18.75 g) to help maintain the quality of the yolk’s texture. Pour the mixture into a jar or other container; then, seal off the top, leaving at least ⁄2 in (1.3 cm) of space between the lid and the surface of the eggs. Once they’re safely packaged, store them in the freezer. Alternative: Pour the egg mixture into an ice cube tray first before transferring the cubes to a moisture- and vapor-resistant container. When thawing: around 3 US tbsp (44 mL) of the egg mixture make up a single egg (or a single egg cube).