How to tell if eggs are bad: 3 simple home tests that really work

There’s something quietly satisfying about cracking open a good egg. The yolk sits bright and proud, the white holds its shape, and there’s that faint, clean scent of freshness. But the moment things go wrong, you know it.

A sharp whiff of sulfur, a thin, greyish ooze, and breakfast is instantly ruined. The tricky part is that eggs rarely look suspicious before they spoil. They hide it well, right up until the moment you crack one. So how do you tell if they’ve gone bad without wasting half the carton or risking your appetite? Scroll down for three simple home tests that actually work, and all you need is what’s already in your kitchen...

1. The float test

This old-fashioned method has been passed down through generations, and it truly works.

All you need is a bowl of cold water. Gently drop the egg in and watch what it does. Fresh eggs sink and lie flat at the bottom - that’s your cue they’re safe and ready to use. Slightly older eggs tilt upwards or stand on one end, still edible, but use them soon.

Eggs that float? Time to say goodbye.

Here’s the science behind it: Over time, air seeps in through the shell’s pores, forming a pocket inside. The larger that air pocket, the more buoyant the egg becomes. Floating means it’s been sitting around too long and spoilage bacteria may have found their way in.

Tip - Always use cold water for this test, warm water can dissolve the natural protective coating on eggs, speeding up spoilage later.

2. The sniff test

When in doubt, trust your nose. It’s one of the simplest, most reliable ways to catch a bad egg. Crack it open onto a clean plate and take a whiff before mixing it with anything else. A fresh egg smells clean, maybe faintly like raw protein or nothing at all. A spoiled egg, on the other hand, carries a sharp, unmistakable odor - sulfuric, rotten, sometimes almost metallic.

If you hesitate for even a second, toss it. That hesitation is usually your nose trying to warn you. If you’re extra cautious, do this before baking or adding eggs to a large dish - better to waste one egg than an entire batter.

3. The visual and texture check

Sometimes, your eyes can tell you what your nose hasn’t yet. Start with the shell. A healthy shell should be matte, smooth, and free from cracks or powdery residue. If you spot anything slimy, sticky, or discoloured, that’s bacterial growth - don’t risk it.

Once cracked, pay attention to what you see on the plate:

A bright, well-rounded yolk and a thick, slightly cloudy white are signs of freshness. A flat yolk or a runny, watery white means the egg is past its prime, though it might still be usable for hard-boiling. Any green, pink, or iridescent tint? That’s contamination. Bin it immediately. And here’s a lesser-known trick - if you gently shake an egg near your ear and hear a sloshing sound, it’s likely old. Fresh eggs don’t slosh; their contents are still tight and firm.

A few storage truths worth knowing

Even the freshest eggs can turn quickly if stored wrong. Always keep them in their original carton, not loose on the fridge door. The carton helps block out moisture and odours from other foods (eggshells are porous, remember?). Store them pointy end down, so the air cell stays at the top, minimising contact with the yolk. And never wash them before refrigeration - washing removes the shell’s natural protective coating, making them spoil faster. For those who like their science neat - refrigerated eggs last about 3 to 5 weeks from the purchase date. Hard-boiled ones, once peeled, last up to a week. Anything beyond that deserves a float test first.