How to Tell If Eggs Are Bad: Sniff Test, Float Test, and Carton Dates
In Short
Here's how to tell if eggs are bad: crack each egg into its own bowl and smell it. Toss any egg that smells of sulfur. The float test only shows age: a fresh egg sinks and lies flat, and an older one stands on end. One that floats is old, so crack it and sniff before you use it.
How to Tell If an Egg Is Bad: The Sniff Test
Crack the egg into a small bowl or cup, not straight into your batter.
Then take a whiff.
A good egg smells like almost nothing.
A spoiled egg smells like sulfur, and you'll know right away.
The University of Nebraska-Lincoln Extension (citing the USDA) says a spoiled egg has an unpleasant odor when you break it open, raw or cooked.
It also says to check for an unusual appearance before you decide.
What a Bad Egg Looks Like
- Off colors or mold: Anything that looks unusual in the white or yolk goes in the trash.
- A cracked or slimy shell: The University of Minnesota Extension says not to use cracked eggs, because bacteria can get in through the shell.
- A thin, runny white: This one is just age. The University of Wisconsin Extension says whites get thinner and yolks flatter as eggs get older.
- A small blood spot: Not a sign of spoilage. UW Extension says it's usually a bit of blood or tissue picked up as the egg formed.
What the Sniff Test Can't Catch
The sniff test finds spoiled eggs.
It can't find Salmonella.
The University of Minnesota Extension says Salmonella can be inside whole, uncracked eggs, which makes it hard to detect.
That's why cold storage and full cooking matter.
UMN says to cook eggs until the yolk and white are firm and reach 160°F.
The Egg Float Test
Fill a bowl with cold water and gently set the egg in.
| What the egg does | What it means |
|---|---|
| Sinks and lies flat on its side | Very fresh |
| Sinks but stands up on one end | Older, still good for most uses |
| Floats to the top | Old, so crack it and sniff before using |
What the Float Test Really Tells You
It's accurate about age.
It isn't a safety test.
UW Extension explains that the float test really measures the size of the air cell inside the egg.
As an egg ages, water evaporates through the shell and that air cell grows, so an older egg floats.
UNL Extension says the same thing about floaters: the egg is old, but it may be perfectly safe to use.
So a floater isn't automatically bad, and a sinker isn't automatically good.
I recommend using the float test to sort, then cracking and sniffing anything you're unsure about.
Candling
Candling means shining a bright light through the shell.
UW Extension says it shows the size of the air cell and any blood spots without breaking the egg.
A strong flashlight in a dark room works at home.
What the Dates on an Egg Carton Mean
Egg cartons can carry up to three dates, and they mean different things.
- Sell-by or EXP date: This is for the store. On cartons with the USDA grade shield, a 2006 USDA rule says it can't be more than 30 days after the pack date.
- Use-by date: This is about peak quality. On USDA-graded eggs, it can't be more than 45 days after the pack date.
- Pack date: The three-digit number on the end of the carton, called the Julian date. It counts the days of the year, so 001 is January 1 and 365 is December 31.
For example, a carton stamped 305 was packed on November 1 (in a year that isn't a leap year).
The USDA's FSIS says fresh eggs keep in the fridge for 3 to 5 weeks from the day you buy them.
The sell-by date will usually pass during that time, and the eggs are still safe to use.
How Long Eggs Last in the Fridge
These are the times from the University of Minnesota Extension's storage chart, for a fridge at 40°F and a freezer at 0°F:
| Type of egg | Fridge | Freezer |
|---|---|---|
| Raw eggs in the shell | 3 to 5 weeks | Don't freeze |
| Raw egg whites | 2 to 4 days | 12 months |
| Raw egg yolks | 2 to 4 days | Yolks don't freeze well |
| Hard-cooked eggs | 1 week | Don't freeze well |
| Cooked egg dishes | 3 to 4 days | 2 to 3 months |
| Egg salad | 3 to 4 days | Don't freeze well |
UNL says to refrigerate hard-cooked eggs within 2 hours of cooking and keep them in a clean container, not the original carton.
To freeze extra eggs, crack them, mix the yolks and whites, and freeze them in an airtight container.
Illinois Extension gives whole eggs out of the shell 12 months.
For more ways to use them up, my beginner's guide to every way to cook eggs covers scrambled, fried, poached, and boiled.
Stacie's Tricks & Tips
- Crack Into a Separate Bowl: One bad egg costs you one egg, not a whole bowl of cake batter.
- Shelf, Not Door: UMN Extension says the door is the warmest spot in the fridge. Keep eggs on a shelf.
- Keep the Carton: It holds the pack date, so you always know how old the eggs are.
- Don't Wash Them: UMN says store-bought eggs are already washed and sanitized, and washing at home can spread bacteria around your kitchen.
- Get Them Home Cold: UMN says to refrigerate eggs within 2 hours of buying them, or 1 hour if it's 90°F or hotter out.
- Skip Sweaty Eggs: Water beads on the shell can mean eggs sat out after being refrigerated, per UMN.
- Save Older Eggs for Scrambles: Their thinner whites spread in the pan, so they're perfect for scrambled eggs or baking. My cottage cheese eggs are a great place to start.
- Out of Good Eggs? My egg substitute guide for baking has swaps that work mid-recipe.
Key Takeaway
Now you know how to tell if eggs are bad, and it takes about a minute.
Open the carton tonight, check the pack date, and crack any questionable egg into a bowl before it goes near a recipe.
While you're cleaning out the fridge, check how long cooked chicken lasts in the fridge too.
Got older eggs that pass the sniff test?
Hard-cook them.
My classic deviled eggs are the ones you'll make again and again.
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Frequently Asked Questions
How do I know if eggs have gone bad?
Crack the egg into its own bowl and smell it. A good egg smells like almost nothing, and a spoiled one smells like sulfur right away. Toss any egg with off colors, mold, or a cracked or slimy shell. A thin, runny white just means the egg is older.
Is the egg float test accurate?
Yes, for age, but not for safety. The test shows how big the air cell inside the egg has grown, per UW Extension. A fresh egg sinks and lies flat, an older one stands on end, and an old one floats. Crack and sniff a floater before using it, since the sniff test is what finds spoiled eggs.
Can I still eat eggs that float?
Yes, if they pass the sniff test. A floating egg is old, not necessarily spoiled, and UNL Extension says it may be perfectly safe to use. Crack it into a bowl first and toss it if it smells of sulfur. Older eggs have thinner whites, so they're perfect for scrambled eggs or baking.
Can I eat eggs 2 months out of date?
No, I'd toss them. UNL Extension, citing the USDA, says fresh eggs keep 3 to 5 weeks in the fridge from the day you buy them. Two months past the carton date is well beyond that. Next time, check the three-digit pack date on the end of the carton to see how old a dozen really is.
How long are hard-boiled eggs good for?
Hard-boiled eggs keep for 1 week in the fridge, per the University of Minnesota Extension. Refrigerate them within 2 hours of cooking. Store them in a clean container, not the original carton. Egg salad made from them keeps 3 to 4 days, and neither one freezes well.
What happens if you eat a bad egg?
You can get food poisoning. A spoiled egg smells of sulfur, so you'll usually catch it before it hits the pan. The bigger worry is Salmonella, which can be inside a whole, uncracked egg. UMN Extension says to cook eggs until the yolk and white are firm and reach 160°F.
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