How to Tell if an Egg Is Fresh: Float Test, Crack Test and Storage

Are the eggs you forgot in the fridge still fresh, or have they gone off? Luckily there are a few simple, reliable tests to tell. And the science behind them is the same as tracking an egg's air cell in incubation. This guide explains how to check egg freshness with the float test, the crack test and candling, how long an egg lasts, and the right storage conditions.

The Float Test: The Best-Known Method

Fill a glass or bowl with cold water and drop the egg in:

• Lies flat on the bottom: Very fresh. The egg sinks and lies on its side.
• Stands upright on the bottom: A bit older but still edible. One end lifts up.
• Floats to the surface: Spoiled — throw it out.

Here's why: as an egg ages, it loses water vapor through the shell's pores and the air cell at its blunt end grows. The growing air cell makes the egg float. This is the very same principle by which we track an embryo's water loss via the air cell in incubation — details in our incubation humidity guide.

The Crack Test: The Most Definitive Method

If unsure, crack the egg onto a clean plate and look:

• Fresh egg: The yolk stands high and domed, most of the white is thick and gathered, and there's no smell.
• Older egg: The yolk is flattened, the white watery and spread out; if it still doesn't smell, it can be cooked and eaten.
• Spoiled egg: A sulfurous/bad smell, a grey-greenish color or cloudiness. If it smells, never eat it.

The rule: smell is the most reliable sign. A bad-smelling egg must be discarded even if it passes every other test.

Candling (Holding to a Light)

In a dark room, hold the egg up to a strong light (a flashlight) and you can see the air cell at the blunt end: small air cell = fresh, large air cell = old. We use the same method to track embryo development in hatching eggs — see the candling guide.

The Shake Test

Shake the egg gently next to your ear: a fresh egg makes no sound (it's full inside). In an old or spoiled egg, the contents have lost water and loosened, so you hear a slight sloshing.

How Long Does an Egg Last?

Storage	Approximate freshness period
At room temperature (unwashed, cuticle intact)	1-3 weeks
In the fridge	4-5 weeks and more
Washed egg	Shorter (must be refrigerated)

These times are approximate; use the tests above for a definite call. The best-before date on the carton is a guide, not an absolute limit — if the tests pass, it can be eaten after the date; if it smells, it must be discarded before the date.

The Right Storage

• Washing: The shell has a natural protective layer (the cuticle) against microbes. Washing destroys it and speeds spoilage. An unwashed egg lasts longer; if you wash it, refrigerate it.
• Position: Store pointed end down; the air cell stays up and the yolk stays centered.
• Odors: The porous shell absorbs strong surrounding odors; keep eggs away from pungent things like onion or fish.
• Temperature stability: If refrigerating, keep them constantly cold; repeated warming and cooling causes condensation.

Hatching Eggs Are Different

An important distinction: eating eggs and hatching eggs are stored completely differently. An eating egg can sit in the fridge for weeks; but a hatching egg you want to hatch a chick from is not put in the fridge (below 10 °C harms the embryo), it's stored at 12-16 °C for at most 7 days. All the rules of hatching-egg selection and storage are in our separate guide.

The Most Common Mistakes

• Eating a smelly egg because it "passed the test" (smell invalidates every test).
• Washing eggs before storing and destroying the cuticle.
• Treating the best-before date as an absolute limit and tossing a fresh egg.
• Storing eggs next to onion/fish and letting them absorb odors.
• Applying eating-egg rules to hatching eggs (putting them in the fridge).

If you've stored a hatching egg correctly and set it, you can track the process day by day in the KuluçkaTakip app. If you want fresh eggs from your own hens, see our when hens start laying and breed selection articles.