How to Tell If Butter Is Bad
Rancid butter smells sour, like old oil or cheese, and may taste soapy or bitter. Butter lasts about 1 to 3 months in the fridge, and mold or fuzzy spots mean it goes in the trash.
Signs Butter has gone bad
- Sour, cheesy, or stale-oil smell. Fresh butter smells creamy and sweet. A sharp, sour, or crayon-like smell means the fat has turned rancid.
- Bitter or soapy taste. A dab on the tip of your tongue will tell the story. Rancid butter tastes harsh and unpleasant.
- Mold spots. Fuzzy green, blue, white, or pink patches mean spoilage. Because butter is soft, throw it out rather than scraping.
- Dark, dry, or crumbly yellow outside. A deeper yellow, dry outer layer is oxidation. If it's only on the surface and the inside smells fine, trim it off; if the smell is off all the way through, discard it.
- Slimy texture. Butter should be smooth and waxy. Any slick, sticky coating suggests bacterial growth.
Looks weird, but it's fine
- Darker color on the outside. This is oxidation from air exposure. Trim the discolored layer away and the rest is generally fine if it smells good.
- Water droplets on the surface. Condensation from temperature swings is harmless. Wipe it off and rewrap.
- Salt crystals or streaks. In salted butter, salt can clump or show as tiny crystals or streaks. It's normal.
How long does Butter last?
| Where | How long | Note |
|---|---|---|
| Fridge (unopened) | 1 to 3 months | Check the date on the package |
| Fridge (opened) | 1 to 3 months | Keep it wrapped and away from strong smells |
| Freezer | 6 to 9 months for best quality | Wrap tightly in foil or an airtight bag |
| Counter | A day or two in a covered dish | Salted keeps longer; don't leave in heat |
How to store it
- Wrap butter tightly or keep it in its original foil, since it soaks up fridge odors like onions and leftovers.
- Keep only what you'll use in a day or two on the counter in a covered dish, and keep the rest cold.
- Freeze extra sticks in a zip-top bag with the air pressed out, and thaw them in the fridge before using.
Use it up before it turns
Frequently asked questions
Does butter go bad if left out?
A small amount in a covered dish is usually fine for a day or two, especially salted, but in a warm kitchen it can turn rancid faster. For safety and quality, keep most of it in the fridge.
How can you tell if butter is rancid?
By the smell and taste. It smells sour, cheesy, or like old oil, and tastes bitter or soapy. Throw it out if the smell is off throughout.
Is it safe to eat butter that has a little mold?
Throw it out. Butter is soft and moist enough for mold to spread beyond what you can see, so cutting it off isn't a good idea.
More food freshness guides
General guidance based on USDA FoodKeeper. Storage times are estimates and conditions vary. When in doubt, throw it out.