Few ingredients are as indispensable as butter, that humble shapeshifter of the kitchen. Whether it’s spread over toast, melted over a seared steak, browned in a pan, or smashed into pastry dough, butter contains multitudes. 

This is precisely why it pays to have a few sticks of butter on hand at all times. But how long will they last you? What kind do you need? And is it true that some people store it in the cupboard, nary an ice pack in sight? 

Butter lasts longer than other dairy products — thanks to its concentration of fat — but it does eventually expire. How and when that happens depends on where you choose to store it. Here’s how to make the most of butter’s unique shelf life.

Does butter expire? 

Yes, butter does expire. Butter’s relatively low moisture levels (usually around 16%) and high concentration of fat (80%) makes it more difficult for bacteria to thrive. If that butter contains salt, there’s an added layer of preservation power that actively prevents microbial growth, slowing spoilage. 

Butter will usually bear an expiration date on its packaging, but remember: use-by, best-by, and sell-by dates are indicators of quality, not food safety. So while it’s best practice to consume your butter before you reach those dates, it’s generally safe to go beyond them, as long as you refrigerate or freeze it. 

A better indicator of true expiration is the appearance, smell, and taste of butter. Spoiled butter can smell (or taste) sour or tangy, and can change in color and texture. Mold or colored spots are a clear indication that butter has gone bad, but even a subtle shift from pale yellow to dark is a sign that it’s time to throw it out. Eating a little bit of rancid butter might result in a harmless (but uncomfortable) stomachache, but a full-on foodborne illness is also possible depending on the severity of the spoilage. 

In some cases, like with aged or cultured butter, you can expect some funkier flavors that are wholly intentional, and even prized depending on where you are in the world. (Moroccan smen, a mixture of butter with herb-infused water, is aged anywhere from a few months to a few decades!) So, assess the state of your butter with a grain of salt. And speaking of salt…there is a difference between unsalted and salted butter when it comes to shelf-life.  

Salted butter 

The presence of salt, a natural preservative that fends off microbial growth, gives salted butter a slight advantage when it comes to shelf life. When well-wrapped, salted butter will typically last one to five months in the fridge, and up to a year in the freezer. Salted butter also lasts a little longer at room temperature, making it the ideal choice for daily uses, like spread on toast.

Unsalted butter 

Without the antibacterial qualities of salt, unsalted butter can be less stable in warmer locations, like the countertop or cupboard. It does still contain protective levels of fatty triglycerides, and will last longer if kept cool. It’s recommended that you keep unsalted butter for one to three months in the fridge, and up to six months in the freezer. 

What’s the best way to store butter?

How you store your butter should reflect how you tend to use it. If you’re a daily toast enthusiast or a daily baker, you may find that keeping one stick out (and softened) for daily use suits you best. If you go for a few days before reaching for it, keeping it in the fridge between uses might be better. If you’re a faithful butter bulk buyer, the freezer is your friend.

How to store butter on the counter

You can store butter on the counter (or the cupboard), with a few caveats. The USDA recommends keeping butter at room temperature for no more than two days — even salted butter, though many of the internet’s home cooks will tell you it can last a week, easily. 

Ultimately, how quickly your butter spoils will depend on two things: your specific kitchen climate, and the storage method you use. 

Counter-stored butter should be kept covered (a ceramic butter dish works great for this) and stored away from direct heat sources, like toaster ovens or gas stoves, since heat, light, and oxidation will speed up spoilage and rancidity. Keeping open or unwrapped butter covered also means it won’t absorb the flavors of its surroundings. 

You can extend the shelf-life of butter that’s been out on the counter for a few days by transferring it to the fridge, but be aware that it’s internal structure may have changed: The texture of butter is an emulsion between water, fat, and milk solids, and you may notice that very soft butter turns grainy or looks separated after you cool it. It’s safe to eat, but may not get you the results you want when used for something like baking, where butter’s components create structure and fluffiness. 

 If you like to have softened butter on hand, but aren’t sure you’ll go through a full stick in under a week, you can also leave out a few tablespoons at a time, and keep the rest in the fridge until you’re ready.  

How to store butter in the fridge

You likely have a few sticks of butter in your fridge at this very moment: It’s a natural spot to extend its shelf-life while keeping it close at hand. When stored in the fridge, butter is held in a temperature-controlled steady state, protected from fluctuations in heat, humidity, and light. 

The same principles of storage apply as those on the counter: Keep open sticks covered or well-wrapped if you can, or risk butter that smells suspiciously of…fridge.

How to store butter in the freezer 

When stored in the freezer in its original packaging (an airtight wrap is key to avoiding freezer burn), butter can last anywhere from six months to a year. The freezer is an ideal solution for bulk buyers, who can reliably avoid last-minute trips to the store by stocking up on both salted and unsalted varieties. 

To soften frozen butter, you can microwave it in small increments, leave it out on the counter, or transfer to the fridge for a slower thaw. Let your method be informed by how you plan to use it. Many baking recipes call for room temperature butter, but since butter thawed in a microwave will alter the effects of the butter itself, give yourself time to bring it to temperature on the counter.

What to do with butter that’s gone bad

Of course, life happens, and some sticks of butter will pay the price. No need to grease the wheels of your local landfill: the Mill food recycler processes food scraps into dry, odorless food grounds that can be added to an outdoor compost pile, picked up by a city-run curbside composting program, or sent back to Mill, where they’ll get it back to the farm.

Sources:

1. Center for Dairy Research, College of Agriculture & Life Sciences at University of Wisconsin-Madison: “Butter Science 101.” Summer 2021. https://www.cdr.wisc.edu/butter-science-101

2. Nordic Food Lab Archive: “Aged Butter part 1: background and basics.” January 21, 2016. https://nordicfoodlab.wordpress.com/2016/01/21/2016-1-21-aged-butter-part-1-background-and-basics/

3. U.S. Department of Agriculture: “Is butter safe at room temperature?” May 16, 2024. https://ask.usda.gov/s/article/Is-butter-safe-at-room-temperature

4. King Arthur Baking Company: “Is it always OK to put softened butter back in the fridge?” December 6, 2022. https://www.kingarthurbaking.com/blog/2022/12/06/is-it-always-ok-to-put-softened-butter-back-in-the-fridge