Hard-boiled eggs smell like farts and go green on the inside.
So it’s pretty easy to mistakenly think they’re off when they’re absolutely fine.
Don’t worry – today, we’ll show you how to identify a hard-boiled egg that has gone off, plus the signs you don’t need to stress about.
Plus, you’ll find more on how to store your hard-boiled eggs and how long they’ll last.
Want the info, and fast?
Hard-boiled eggs have gone bad if they have a slimy or powdery shell, an unusual smell, or discoloring. However, a gassy odor and a greenish-gray ring in the yolk are normal.
How To Tell If Your Hard-Boiled Eggs Have Gone Bad

First, if your egg is hard to peel, that’s actually good because it means it was fresh when boiled.
These are the indications that your egg has gone bad:
- A slimy, chalky, or powdery shell is a sign that bacteria is looming.
- A weird smell when you crack your egg open.
- Dark brown, black, or green spots
You might be wondering: what’s the gross-looking greenish-gray hue to my yolk?
Although it might not look the most appealing, the color of the yoke varies depending on cooking time and temperature. When eggs are cooked for a long time, the yolk goes pale and eventually turns greenish-gray since the iron from the yolk reacts with the hydrogen sulfide in the white.
Therefore, a green or gray coloring to your yolk is nothing to worry about.
However, if you get any food poisoning symptoms – like diarrhea, nausea, or vomiting – seek medical assistance immediately.
How To Store Hard-Boiled Eggs

The first step to ensuring you store a hard-boiled egg perfectly is to find a good egg to hard-boil. This is how to tell if a raw egg is fresh:
- Check the expiration, best before, sell-by, and Julian dates on the carton. Julian dates are represented with a number 1-365, each number chronologically standing for a day of the year. If you’re within 21-30 days from the pack date, your eggs should be good to hard-boil.
- Look for slimy or powdery shells, signs that bacteria has been growing.
- Float Test: Put your egg in a bowl of water. If it sinks, it’s fresh, but if it tilts upwards, it’s old. Remember, this is only a test of how old your egg is, not how good or bad it is.
Now that you know how to choose a fresh egg to hard-boil, you’re ready to go.
You should hard-boil, not soft-boil, your egg to help preserve it. There are plenty of different methods you can follow to hard-boil an egg, but here’s the failsafe version:
- Put eggs in a single layer in your saucepan and cover with cold water. The eggs should be covered by at least 1-2 inches of water.
- Add ½ tsp of salt or 1 tsp of vinegar, if required. Salt will make your eggs easier to peel and prevent cracking, while vinegar will stop the whites from running out of the egg when cooking.
- Bring the water to a rolling boil.
- Cover your saucepan and turn the hob off without moving your saucepan away from the stove. Wait 10-12 minutes.
- You’re now the owner of a perfectly hard-boiled egg, ready for it to go into storage!
The shell is the best barrier between the yolk and white and the outside world. Therefore, you shouldn’t peel your egg until it’s ready to be used.
During the boiling process, the protective layer of the shell is removed, meaning the egg inside is more vulnerable to bacteria. Therefore, you should refrigerate your hard-boiled eggs within 24 hours of cooking – any temperature above 40 ° F (or 4 ° C) and bacteria will grow fast on your egg.
Because of this, you should store your hard-boiled eggs in an airtight container within the refrigerator, but not the fridge door, as this is the area most prone to temperature fluctuation.
You might notice an initial gassy odor from the hydrogen sulfide emitted by your egg. But don’t worry, this is completely harmless and should go within a day.
Unfortunately, freezing’s not a good idea for your hard-boiled egg. It will go tough and watery.
Accidentally peeled a hard-boiled egg before you’re ready to eat it? Place it in an airtight container with a damp paper towel in the refrigerator to stop it from drying out.
How Long Hard-Boiled Eggs Last

According to the USDA, peeled or unpeeled hard-boiled eggs last for one week in the refrigerator.
Eggs that you buy pre-peeled at the supermarket will only last 2-3 days after opening the package and should always be stored in the fridge.
Remember, soft-boiled eggs spoil faster. Expect them to last up to four days in the refrigerator.
Eggs, Cracked
Now you know how to pick, cook, and store a hard-boiled egg like a pro. Remember the key rules:
- Your hard-boiled egg will last for one week in the refrigerator.
- Hard-boiled eggs aren’t suitable for freezing.
- A greenish-gray color is nothing to worry about. However, any slime, weird smells, or other colors and your egg should go in the bin.