It seems to be common knowledge among bakers that salted butter has a higher water content than unsalted*. How much higher?

And if there's a different amount of water, why does this nutritional data say there's the same amount of fat in salted and unsalted butter? (I'm fairly sure I've seen the same on butter in the store, and I'll try to remember to confirm that next time I'm there.)

*I'm pretty sure I remember seeing the claim several places online, but the one I was able to quickly find is from Cook's Illustrated (click to expand the second-to-last question) via an answer here, saying that "salted butter almost always contains more water than unsalted butter". (It's possible that a lot of other people's knowledge ultimately came from there.) The nutritional information I've found, along with my own baking experience, does not back this up, but Cook's Illustrated is generally pretty trustworthy, hence the question.

  • I've never heard such a thing. Searching around is only turning up anecdotal evidence ("I was told by this pastry chef..."). Now you've got me curious.
    – JoeFish
    Commented Jul 12, 2012 at 20:35
  • Closest I've got so far is Land o' Lakes' FAQ: Salted and unsalted butter can be used interchangeably.
    – JoeFish
    Commented Jul 12, 2012 at 20:43
  • 1
    Makes no real sense. There is no standard anyway, water and salt levels vary by batch. Each supplier does it differently
    – TFD
    Commented Jul 12, 2012 at 20:59

2 Answers 2


The FDA definition for butter specifies only that it be made exclusively from cream or milk, contain a minimum of 80% butter fat by weight, and may include salt and coloring.

FDA Butter Definition

USDA Butter Standards

If you assume the butter in question is at the low end of the spectrum with exactly 80% fat and equal amounts of milk solids, then unsalted would have less water than salted. Since there is no standard that says milk solids must also be a specific percentage, or that fat content can only be 80% and no more, there is really no way to accurately make the claim that salted butter always contains more water than unsalted.

  • This is the best I could figure out too. I was really hoping for some explanation of that claim from Cook's Illustrated, though!
    – Cascabel
    Commented Jul 18, 2012 at 3:26

I have read that by French law, salted butter is allowed a lower fat content. From the New York Times: Butter With a Pedigree. Ah, the French:

The most obvious difference is butterfat: By law, American butter must contain at least 80 percent, while the minimum for French butter is 82 percent (unless it is demi-sel, or salted butter, which can check in at 80 percent and include up to 2 percent salt). Two percentage points may sound measly, but since butterfat affects butter's flavor, texture and workability, every little bit counts.

This is speculation, but perhaps the folk wisdom of unsalted butter having higher fat content may have some basis in fact, at least outside of the US.

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