Ahh, butter. One of the most popular types of fat, butter is a vital ingredient in cookies, the perfect spread for freshly baked bread, and a staple ingredient in SO many other foods.
While there are many spins on butter (buttery spreads, margarine, vegan butter, etc.), how long does REAL butter made from cow’s milk (no added oils, maybe just a touch of salt) last after you open it?
Butter stays good until its best-by date and even a couple of weeks past, even once you open it!
For all the deets on how long butter will last after you open it, keep reading!
What is the shelf life of butter?
Butter made from pasteurized milk has an impressive shelf life for a dairy product. If you use butter made from unpasteurized (raw) milk, its shelf life will be shorter because it’s more prone to bacterial growth. For the sake of this article, when we say “butter” we’re referring to butter made from pasteurized milk, which is overwhelmingly the most popular type.
While the best-by or use-by date will vary depending on when you bought the butter and when it was packaged, packaged (sealed) butter is generally good for around six months in the fridge. (We busted out a brand new box of butter while writing this out of curiosity, and its best-by date is over 5 months from the purchase date!)
Once you open butter it can lose its freshness and quality, even though it might not go “bad” until after the best-by date. To get the longest shelf life out of butter, pop it in the freezer where it will stay good for around one year!
Salted butter might last slightly longer than unsalted butter (salt acts as a preservative), but not enough to make a significant difference.
Summary of butter’s shelf life
| Shelf life | Room temperature | Unopened in the fridge | Opened in the fridge | Sealed in the freezer |
| Butter (made from pasteurized cow’s milk, salted and unsalted) | 1-2 days (per USDA) | ~1 month past best-by date | ~2 weeks past best-by date | Up to 1 year |
How do you know if butter has gone bad?
Butter doesn’t go rancid very quickly, but it can. (Going rancid is the process where the fat chains in butter break down, which causes its flavor to decline.)
You can tell butter has expired by giving it a taste test. The delicious butter flavor we all know and love will be replaced with a sour or bitter flavor if it’s gone bad. You can also spot signs that butter is past its prime by looking out for things like:
- Changes in color, such as darkening.
- A change in texture.
- An unpleasant odor (butter can absorb odors of the things it’s stored near, which is why keeping the butter sealed is so important!)
What happens when you eat butter that has been open for a long time?
Eating butter that’s been open a while and is past its best-by date isn’t likely to pose any serious risk. You might not even realize the butter isn’t fresh until you’ve eaten a few bites (or a lot – we’re not judging) and wonder what you should expect.
The good news is that you aren’t likely to get seriously sick from eating past-its-prime butter, unlike more perishable foods like meat. You might end up with a stomach ache and other digestive discomforts by eating older butter, and also a lesson learned!
Potential risks of eating butter that has been open for a long time
Besides getting an upset stomach, the quality and flavor of your food and baked goods might suffer by using butter that’s been opened for a long time. For instance, your Grandma’s chocolate chip cookie recipe might not taste as good if you’re using butter that has taken on the odor of the leftovers it’s next to in the fridge.
Bottom line – how long does butter last after you open it?
Okay, so how long can you expect butter to last after you open it?
Butter will last a couple of weeks (and up to a month) past the best-by or use-by date when stored in the fridge. Its quality might decline slightly if you wait until then to finish using it.
If you like to store butter on the counter at room temperature, the USDA recommends using it within 1-2 days, though anecdotally many people keep it out longer without any issues.
FAQs:
If butter is two months past its best-by date, it’s likely lost its ideal freshness and quality. While you probably won’t get sick from using it, it’s not recommended to use it that far past its best-by date unless it has been stored in the freezer.
After opening, keep butter tightly sealed to keep it fresh, but know that opened butter will last until its best-by date and even a couple of weeks past it in the fridge! Avoid storing opened butter in the fridge without covering it well because it can take on odors from other foods in your fridge.
Butter kept in the fridge will last until its best-by date and even a couple of weeks past it.
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