Do you ever round up all of the exotic ingredients you need for a baking project (Rooibos tea leaves! Golden syrup! Prune butter!), completely overlooking the basics? Obviously have butter, you think.
Except you return home, flushed on the high that is tracking down goat milk, only to realize you have salted butter, and the recipe calls for unsalted. Or the other way around. So it's time to get creative: Can they be used interchangeably by adding or reducing the amount of additional salt used?
The short answer is yes, sort of—read on to find out the nitty gritty.
First, it's important to know the differences between salted and unsalted butter:
Since salt acts as a preservative, the shelf life of salted butter is actually longer than that of its unsalted counterpart (about 5 months and 3 months, respectively).
While the standard estimate is that salted butter contains 1/4 teaspoon of salt per 4 ounces of butter (1 stick), salt levels actually range widely from brand to brand.
The type of salt in salted butter varies widely, too—you can find brands made with sea salt, fleur de sel, and regular old table salt.
Cooks’ Illustrated lists another problematic difference: “Salted butter almost always contains more water than unsalted butter.” In baking, water can interfere with gluten development, so the less water, the better. In fact, when Cooks’ Illustrated tested biscuits made with unsalted and salted butter, tasters noticed a difference not only in flavor, but in texture. The additional water in salted butter produced samples that tasters found “mushy” and “pasty.”
To test out all of these claims, I made two batches of simple sugar cookies (a recipe that calls for unsalted butter) and two batches of David Lebovitz's Salted Butter Chocolate Chip Cookies (which calls for salted). For both, I made one version with Land O'Lakes unsalted butter, the other with Land O'Lakes salted butter.
When testing the sugar cookies, I was interested in differences when salt levels are more or less equal, so I did a bit of math (ugh) and worked out how much salt I needed to add for the salted butter version.
The original recipe with unsalted butter calls for 1/2 teaspoon of salt, so I needed to add .31 teaspoon to the salted version. They make a separate spoon for that, right?
There wasn't a discernible difference between the two doughs, but once baked, the cookies were visibly different. The ones with unsalted butter were more golden with a crispier edge (and more closely resembled the photo attached to the recipe). The salted butter ones were pale and a bit doughier in appearance.
But how'd they taste?
Tasters found the unsalted butter version crispier, crumblier, and the right amount of chewy. They also found them saltier. Tasters found the salted version cake-ier and overall chewier. But when tasters guessed which cookie was which, almost all of them were wrong.
More: We can't turn down a good butter taste test.
David Lebovitz, the beloved baker and blogger, has written about his fondness for baking with salted butter. He uses it in chocolate sauce, in ice cream, and in chocolate chip cookies. He prefers the European-style butter flecked with fleur de sel or grey sea salt.
Lebovitz says that butter has a more "distinct buttery taste." Our co-founder Amanda Hesser agrees, with a caveat:
"I [use salted butter] when I want to add a fully savory element to a cake. I used to add salt separately but found that it doesn't always blend in. In some cookies and desserts, it's great to come across the crackle of a salt crystal, but it doesn't work well universally."
Lebovitz seems to have been looking for just that—the crunch of a salt crystal—in these cookies, which call for a combination of salted butter and flaky sea salt. For the unsalted version, I went with the standard estimate (1/4 teaspoon) to compensate for the salted butter. In both, I added 1/2 teaspoon Maldon salt.
How'd they taste?
Tasters found the version with the unsalted butter a little more golden, a little doughier, and a little more universally salted. Folks found the salted version richer and more buttery, but ultimately liked the unsalted butter version better.
Just like last time, most tasters incorrectly identified which cookie contained which butter. Why might that be? As one taster told me, "I just like salted butter better, so I'm looking for the saltier cookie."
Bottom line: All the cookies worked, but it’s best to use unsalted butter if the recipe calls for it—and maybe even if it doesn't.
In both tests, the majority of tasters preferred the unsalted butter cookies, which most of them thought were the salted butter version. This may be because the amount of salt was more precise in the unsalted butter cookies. Salt does more than just contribute "saltiness"—it brings out flavors of other ingredients, so measurements are important here.
CI was right: The cookies made with salted butter had a noticeably different texture than ones made with unsalted butter, particularly in the sugar cookie test. This is likely due to the differences in water content, which can range from 10 to 18%. Fat levels can affect water content, too (check out Kim Severson's findings comparing butterfat in the SFGate). But since I used Land O'Lakes butter—which is 80% fat in both the salted and unsalted types—variations in butterfat shouldn't have affected water volume.
It was pretty difficult to find a baking recipe that called for salted butter, suggesting that recipe writers prefer the control that comes with using unsalted. Writes Lebovitz:
"I’m using [salted butter] more and more in baking, although I have to temper that with the fact that salted butter varies wildly from place to place, so in most recipes, I still generally call for unsalted butter."
If attempting a Napoleon Cake, for instance, you should probably just follow the directions exactly.
But if you’re in a pinch, go ahead and sub one for the other. Check the label for nutrition information or hop online to determine the sodium levels you’re working with. It's a tedious step, but the standard advice to "just leave out the added salt" when subbing in salted butter can't be followed considering the variations between brands of butter.
Do you have any tips or thoughts on swapping unsalted butter for salted? Do you secretly always baked with salted butter? Tell us in the comments!