When it comes to eggs, there can be a lot of confusion about which ones are safe to eat and which aren’t.
Have you ever put boiled eggs into boiling water, only to have them float instead of sink? It’s an odd occurrence that can leave many wondering if they should still eat them.
This floating phenomenon is connected to the age of the egg and the presence of an air pocket inside its shell.
Over time, the egg’s moisture content diminishes, gradually enlarging the air pocket. Consequently, the buoyancy of an older egg increases, causing it to float.
This occurrence typically indicates that the egg may be old, potentially spoiled, and harmful to consume. Food poisoning from rotten eggs can lead to gastrointestinal issues, such as stomach aches, vomiting, and diarrhea.
Therefore, it is essential to identify whether floating boiled eggs are safe to eat, significantly reducing the likelihood of ingesting harmful bacteria and avoiding potentially unpleasant consequences on our bodies.
In this post, we’ll dive deeper into the details surrounding boiled eggs that float and explain why it happens and what you need to know before deciding whether or not they’re edible.
Table of Contents
The Science Behind Why Some Boiled Eggs Float
Boiled eggs float in water because of a phenomenon known as “buoyancy.” Buoyancy is the upward force that a fluid, like water, exerts on an object. This means that when an object is placed in water, the liquid exerts an upward force. When this force is greater than the object’s weight, it will float.

This same principle applies to boiled eggs. The air cell inside a boiled egg expands during cooking and causes the egg to become less dense than regular raw eggs.
This decrease in density allows the egg to float when placed in water because its buoyancy is more significant than its weight.
The amount of air cell expansion depends on how long you cook the egg and at what temperature.
If you over-cook your eggs, then too much air will enter inside them and cause them to become very light and buoyant, making them float more quickly than usual.
On the other hand, if you undercook them, there will not be enough air inside them, and they will sink to the bottom of your pot or bowl when placed in water.
Age Of The Egg
An egg’s age is another factor that can affect its ability to float in water. Generally, the older an egg is, the more air will be built inside its shell. As an egg ages, tiny pores in the body allow oxygen and other gasses to enter and naturally accumulate over time.
As a result, older eggs will have more air inside them than younger eggs, which may be more likely to float when placed in water.
Some studies have also suggested that old eggs may contain higher levels of carbon dioxide which could also increase their buoyancy in water.
Scientists believe this higher level of carbon dioxide is because older eggs contain weaker shells, allowing for more gas exchange between the air and the egg whites.
These findings suggest that age can play a role in determining how well an egg will float in water, with older eggs having a greater tendency to rise than younger ones.
The Temperature Of The Water Used To Boil The Egg
The water temperature used to boil the egg is also essential in determining whether an egg will float or sink. Generally, when the water is hotter, it will have a higher density and provide greater buoyancy.
This means eggs boiled in hot water are more likely to rise to the top than those cooked in cold water.
How To Test Whether a Boiled Egg Will Float or Sink
Testing whether a boiled egg will float or sink can be done by following these steps:
- Fill a bowl with room-temperature water. It is important to use room temperature water because it allows the egg to cool evenly when placed in the water.
- Place the egg gently into the water bowl, ensuring the pointy end goes in first.
- Observe what happens to the egg after you place it in the water bowl. The egg is hard-boiled if it sinks to the bottom and lays flat. If it bobs in the bowl or stands up vertically, it is not fully cooked yet and needs more time in boiling water.
- Remove the egg from the bowl and tap it lightly against a hard surface such as a plate or countertop to determine if an uncooked white remains inside, indicating that more boiling time is needed for a hard-boil result.
- If the egg is fully cooked and does not sink to the bottom of the bowl, then it will float! If this is the case, you have a perfectly-boiled egg ready to be served.
Are Floating Eggs Safe to Eat?
Potential health risks associated with consuming a floating egg
Floating eggs may be safe to eat, but there are potential health risks associated with consuming them. Floating eggs typically indicate that the egg has gone wrong and could have been contaminated with bacteria such as Salmonella.

Consuming a floating egg could cause food poisoning, leading to vomiting, diarrhea, cramps, fever, and other serious complications.
Discarding eggs that float in water and avoiding eating them for safety reasons is essential.
It is also essential to practice good food safety habits when handling and preparing eggs since fresh eggs can contain pathogens like Salmonella.
These habits include washing hands often while handling raw eggs, cleaning any utensils or surfaces that come in contact with raw eggs immediately after use, thoroughly cooking the egg until both the white and yolk are solid, and storing the boiled egg immediately in a refrigerator at 40 degrees F or below.
Following these food safety guidelines can help minimize the risk of becoming ill from consuming eggs.
What to do if you have already eaten a floating egg
If you have already consumed a floating egg and feel unwell, seek medical attention immediately.
Treatment for food poisoning will depend on the severity of your symptoms.
Staying hydrated and getting plenty of rest is essential until you feel better. If symptoms worsen or do not go away after a few days, contact a doctor for further evaluation.
In conclusion, floating eggs are unsafe to eat and can cause food poisoning. It is essential to practice good food safety habits when handling and preparing eggs and to seek medical attention if you have consumed a floating egg and feel unwell.
How to Ensure That Your Boiled Eggs Sink
Steps to take to ensure that your boiled eggs sink
Following a few simple steps is essential to ensure your boiled eggs fall.
- Use fresh eggs for boiling. Older eggs can create gas which can make them float when cooked. Older eggs also tend to have weaker shells which can cause the egg white and yolk to leak out during boiling, making them more likely to float.
- Use enough water when boiling the eggs so that they are fully submerged beneath the surface. If there is insufficient water, the eggs may not sink all the way.
- Be sure not to overcook the eggs, and add a teaspoon of salt or vinegar to the boiling water as this can help keep the egg whites from leaking out during cooking and make them more likely to sink after boiling.
- Once finished boiling, allow the eggs to cool before handling as this will help them return down if any have floated during boiling due to trapped air bubbles in the shell.
- Finally, a quick test can be done by gently tapping each egg with a spoon after cooling – if an egg sinks quickly, then it should be safe for consumption; however, if it takes time and doesn’t sink immediately, then it should be discarded as this could indicate that the egg has gone bad and is no longer safe for consumption.
Tips for boiling eggs perfectly
Boiling eggs ideally requires following some essential steps. To start, choose fresh eggs and use enough water so that the eggs are completely submerged underneath the surface.
Adding a teaspoon of salt or vinegar to the boiling water can help keep the egg whites from leaking out during cooking and make them more likely to sink after boiling.
Setting a timer is essential once boiling, so you don’t overcook your eggs. The exact cooking time depends on your preferred level of doneness and the size of the egg: large eggs take around 9 minutes to achieve a hard-boiled state, while smaller ones require about 7 minutes of cooking time.
Adding a few drops of vinegar at the start of cooking is also recommended, which helps keep egg whites firm during boiling and prevents them from spreading out in case of cracks in the shells.
When finished cooking, immediately transfer boiled eggs into an ice bath to stop them from continuing to cook, and turn off the heat source completely. This will help ensure that you get perfectly cooked hard-boiled eggs every time.
Finally, when handling boiled eggs, it is important not to tap or shake them as this can cause cracks in their shells, leading to the leakage of their contents during boiling.
The Nutritional Value of Boiled Eggs
Boiled eggs, often considered simple and humble, have abundant nutritional benefits that do wonders for our health.
An excellent source of high-quality proteins, they contribute significantly to the growth and maintenance of healthy muscles and tissues. Rich in essential vitamins and minerals, including antioxidants that promote eye health, boiled eggs offer nutrients like vitamins A, D, and B12, riboflavin, and selenium.
They also provide essential fatty acids, such as omega-3, crucial in maintaining proper brain and heart health. As a low-calorie food option, incorporating boiled eggs into your diet can help you achieve weight management goals while obtaining the necessary nutrients for a balanced and nourishing lifestyle.
Recommended daily intake of boiled eggs
The daily recommended intake of boiled eggs depends on various factors such as age, gender, and activity level. Generally speaking, it is generally accepted that adults should consume two to three boiled eggs per day for optimal health benefits.
Children between the ages of 6 and 12 should have one to two boiled eggs daily, while adolescents and pregnant women should aim for around three to four boiled eggs daily. However, it’s important to remember that these figures may vary according to nutritional needs.
How to incorporate boiled eggs into your diet
Incorporating boiled eggs into your diet is quite simple, as they provide a wealth of nutritional benefits that are easy to access. Whether you have them boiled, poached, scrambled, or even made into an omelet or quiche, there are various ways to enjoy boiled eggs.
For breakfast or brunch, incorporate boiled eggs on top of avocado toast for added protein and flavor. You can also create a delicious egg salad by mixing boiled eggs with mayonnaise and chives for a nutrient-packed lunch.
Alternatively, you can whip up an egg-based frittata or breakfast burrito filled with vegetables like diced tomatoes and spinach for a more savory option.
If you’re looking for an easy snack between meals, hard-boiled eggs are an ideal choice. Simply peel and slice the eggs in half lengthwise and season them with salt and pepper for a tasty snack on the go.
Add chopped boiled eggs to homemade salads or sandwiches for flavor and nutrition.
Regardless of how you prepare boiled eggs, it’s important to remember that moderation is key when consuming any food item.
Even those packed with health benefits like boiled eggs! It’s also important to note that eating too many eggs can increase your cholesterol levels over time if consumed in excessive amounts.
Frequently Asked Questions
What does it mean when a boiled egg floats?
When a boiled egg floats, it usually means that the egg is old and air has leaked inside and caused it to become less dense. This results in the egg floating in the water instead of staying submerged. Older eggs are still safe to eat but may have a watery, greenish-gray inner ring around the yolk.
Are all floating eggs unsafe to eat?
No, not all floating eggs are unsafe to eat. Eggs that float may indicate that they are fresh, as a fresh egg has more air space inside the shell than an older egg.
However, eggs left out for too long or those with cracks should be thrown away since bacteria can enter the egg through these openings. Therefore, it is best to conduct a sniff test before consuming any egg to make sure it does not smell off or spoiled.
How do you know if an egg is bad after boiling?
After boiling, you can tell if an egg is rotten by looking for sure signs.
If the egg has a foul odor, pungent smell, or strange coloration, it should be thrown away. Generally, a boiled egg that is still safe to eat will have a firm white and yolk with no visible discoloration.
If the egg appears watery or has dark rings around the yolk, this indicates spoilage from bacteria growth and can also be unsafe to consume.
If it floats in water, it should not be eaten because air seeps into its shell, which could cause bacteria growth.
What should you do if you accidentally eat a floating egg?
If you accidentally eat a floating egg, look for signs indicating the egg has gone bad, such as a foul odor or strange coloration. If you experience any of these signs, seek medical attention immediately. Other than that, there is no need to take any particular action unless a doctor advises.
How long do boiled eggs last?
Boiled eggs will last up to one week when stored properly in the refrigerator. It is essential to keep them in a sealed container or covered with water to prevent them from drying out and consuming them within seven days of preparation.
Cooked eggs should not be left out of the refrigerator for more than two hours as this can increase their risk of spoiling. To check if boiled eggs have gone bad, look for visible signs like discoloration or a foul odor before eating them.