How to tell if an egg is still good: the float test

The egg float test is a handy kitchen check, especially when the box has gone missing or the date is hard to read.

Just use it for what it is: a freshness test, not a food safety test. The Food Standards Agency is clear that the float test tells you how old an egg is. It cannot tell you which bacteria may or may not be inside.

How to do the egg float test

Fill a bowl or a large glass with cold water. Gently lower the raw egg into the water.

If the egg sinks and lies flat on the bottom, it is fresh. If it sinks but tilts or stands upright, it is older and should be used soon. If it floats to the surface, do not use it.

Why does this work? Eggshells are porous. Over time, moisture and gases escape through the shell, air gets in, and the air cell at the rounded end of the egg grows. The older the egg, the more likely it is to stand upright or float.

Still, the water test is only the first check. If the egg sinks, crack it into a separate bowl before adding it to your recipe. Look at it and smell it. If anything seems wrong, throw it away.

The float test at a glance

Position in the water	What it usually means	What to do
Sinks and lies flat	Fresh	Good for most uses. For raw or runny dishes, use in-date British Lion or Laid in Britain eggs.
Sinks but the tip rises	Less fresh	Use soon. Fine for cooking and baking if it looks and smells normal.
Stands upright on the bottom	Old, but not necessarily spoiled	Use quickly and cook thoroughly: cakes, well-cooked omelettes, hard-boiled eggs.
Floats to the surface	Very old	Do not use it.

These are rough signs, not exact ages. Storage conditions matter a lot, especially temperature.

Does a floating egg mean it is rotten?

Not always. A floating egg is old because its air cell has grown large enough to make it buoyant. That does not automatically mean it is rotten.

The problem is that a floating egg has already failed the freshness check. It may also be past its best-before date, or you may not know how it has been stored. Since the float test cannot tell you whether bacteria are present, the sensible kitchen rule is simple: if it floats, do not use it.

Other useful checks

Shake the egg next to your ear

A fresh egg should make little to no sound when shaken gently. If you hear sloshing, the white has thinned and the air cell has grown. It is another sign that the egg is old.

Do not rely on this test alone. Use it as an extra clue, not as a final decision.

Crack it into a separate bowl

This is the final check whenever you are unsure. A fresh egg has a thick white that holds together and a rounded yolk. An older egg has a thinner white that spreads out and a flatter yolk. It can still be usable if it smells normal and is cooked thoroughly.

A sulphurous smell, or any unusual pink, green or black discolouration, means the egg should be thrown away immediately. Never crack a doubtful egg straight into cake batter, pancake mix or a pan with other ingredients. One bad egg can ruin the whole dish.

What does the date on an egg box mean?

In the UK, eggs carry a best-before date, not a use-by date. That matters.

A use-by date is about safety. A best-before date is about quality. Food can often be eaten after a best-before date, but it may not be at its best.

For eggs, the best-before date is set at 28 days after laying. Shops must also get eggs to the consumer within 21 days of laying, which normally leaves at least a week before the date on the box.

The Food Standards Agency says eggs can be eaten for a couple of days after the best-before date if they are cooked well. That means both the white and the yolk should be firm. Eggs just past their date can also be used in dishes that will be fully cooked, such as cakes.

After the best-before date, avoid homemade mayonnaise, mousse, tiramisu, runny fried eggs, soft-boiled eggs and any dish where the egg stays raw or runny.

To understand the difference between date labels, read our article Use-by vs best-before dates: what’s the difference?

A note on British Lion eggs

For UK readers, the British Lion mark is more useful than the term “extra fresh”.

British Lion eggs are widely sold in UK supermarkets. According to the British Egg Industry Council, more than 90% of UK eggs are produced under the British Lion scheme. The Food Standards Agency says British Lion eggs, and eggs produced under the Laid in Britain scheme, can be eaten raw or lightly cooked by most people if they are still within their best-before date.

That includes infants, children, people who are pregnant and people aged 65 or over. The exception is people who are severely immunocompromised and need medically supervised diets.

This is why the advice is not simply “always cook every egg hard”. For an in-date British Lion egg, a runny yolk is not the same situation as an egg that is already past its best-before date.

Once the date has passed, follow the FSA’s more cautious advice: cook it well, until both the white and yolk are firm.

What about “extra” or “extra fresh” eggs?

Egg marketing rules include the terms “extra” and “extra fresh” for a short period after laying. In practice, UK shoppers do not see these labels very often.

So it is useful legal context, but not the clearest shopping advice for a UK audience. In a British supermarket, most people will look first at the best-before date and, where present, the British Lion mark.

How to keep eggs fresh for longer

1. Keep eggs at a constant temperature, ideally in the fridge. Temperature swings can cause condensation on the shell.
2. Keep them in their original box. It protects the eggs, keeps the date visible and helps stop fridge odours being absorbed through the shell.
3. Avoid the fridge door if possible. It is usually the place with the most temperature changes.
4. Do not wash eggs before storing them. If a shell is dirty, cracked or damaged, do not use the egg.
5. Store eggs away from raw meat.
6. To freeze eggs, do not freeze them in the shell. Crack them into a sealed container first. You can beat them together or separate whites and yolks.

Stop finding forgotten egg boxes at the back of the fridge

The float test is useful when the date is unknown, the box has been thrown away, or the eggs are close to their best-before date. The easier habit is to avoid reaching that point.

That is where an app like Date Limite helps. Scan the barcode on the box, record the best-before date once, and get a reminder before it arrives.

Use the freshest eggs for poached eggs, soft-boiled eggs and runny yolks. Use older but still good eggs for cakes, hard-boiled eggs and well-cooked omelettes. Less waste, less guesswork, and no unnecessary risk.

Key takeaways

A fresh egg sinks and lies flat. An egg that stands upright is old and should be used soon. A floating egg should not be used.

The float test tells you about freshness, not safety. Always crack a doubtful egg into a separate bowl and check its smell and appearance.

Eggs have a best-before date, not a use-by date. After that date, the Food Standards Agency says eggs should only be eaten for a couple of days and only if cooked well, until both the white and yolk are firm.

For storage: keep eggs cool, dry and at a constant temperature, ideally in the fridge. Leave them in their original box and do not wash them before storing.

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Sources: Food Standards Agency: Home food fact checker; Gov.uk: Best before and use-by dates; retained Regulation (EC) No 589/2008, marketing standards for eggs; retained Regulation (EC) No 853/2004, hygiene rules for food of animal origin; Egg Info: British Lion eggs; Egg Info: Egg storage and handling.