Generally , you should use unsalted butter.
You can always add salt to your unsalted butter, but you can't take it out if you want it less salty!
If it's just being melted on some vegetables, then salted butter is probably fine.
However, different brands of salted butter have different amounts of salt added, which makes it difficult to know how much total salt is going into your food.
This is more problematic in baking.
It's possible to easily oversalt or undersalt just by using a different brand — leading to unpredictable results.
By using unsalted butter, the only salt remaining in the recipe is what you have added, and you have more careful control over the outcome.
If you need to substitute one for another, you can estimate how much salt is in salted butter and adjust your recipe accordingly.
If you are not sure whether a particular recipe calls for salted or unsalted, look for clues.
Is there additional salt in the recipe?
(If not, it may expect some salt from the butter.
If so, it may expect unsalted butter!)
How old is the recipe?
(Newer recipes tend to assume unsalted butter.
Older recipes tend to assume salted butter.)
Where was the recipe written?
Different cultures assume different butters (and salt levels may vary between countries for salted butter!); I will not give an exhaustive list here, mostly because I don't know, but it's worth researching.
If you have the time, interest, and money, you can try making the recipe twice (once with salted, once with unsalted butter) and see which tastes better.
This is a bigger investment, though, so only worth doing if you really want to get the recipe as good as possible.
cooking.stackexchange.com/users/17272/Erica
It does matter, using salted butter changes the salt content of the dish, which will change the flavor.
It probably won't greatly affect the chemistry of a dish aside from that, however.
In my experience it's much more common to see unsalted butter in recipes, so I almost always default to unsalted if the recipe doesn't specify.
If they meant salted butter
and I use unsalted, I can usually fix it by adding salt.
The only real advantage of salted butter is its longer shelf life.
cooking.stackexchange.com/users/54276/SuperWild1
Good question!It depends on the dish being made.
Easy rule of thumb: Savory/seasoned as a main dish or meat = salted butter Sweet, fruit or greens heavy = unsalted Also
- you can make melted/browned butter easily, by slowly melting the butter
so you have a stable cooking medium.
cooking.stackexchange.com/users/70083/user2687498
This may be somewhat country-specific.
Here in the UK, sweetness levels which may be considered normal for the US palate are generally considered overkill here.
Using salted butter can provide a balance to the flavour which is missing in unsalted butter.
Adding salt separately can solve that problem, of course.
But with salt levels being relatively consistent in butter over here, and with most people who do use real butter as a spread using salted butter, my experience is that UK recipes are more likely to assume salted butter unless otherwise stated.
cooking.stackexchange.com/users/43471/Graham
In the UK, if a recipe just calls for "butter", it is asking for salted butter.
This is because historically all butter was "salted butter", with "unsalted butter" being very expensive before the advent of refrigeration due to its low shelf life.
Additionally, the majority of products labelled "butter" will be salted butter, with the unsalted butter being explicitly labelled "unsalted butter", e.g. Compare the marketing of major brands in the UK in their use of butter vs unsalted butter: http://www.kerrygold.co.uk/home/products/ https://www.arlafoods.co.uk/brands/butter-and-spreads/
https://www.dairycrest.co.uk/brands/butters-spreads-oils/country-life/ Here is another source: https://www.statista.com/statistics/301909/leading-brands-of-butter-in-the-uk/
What's interesting is that, with the prevalence of internet-based recipes from the US and other English-speaking countries, the term "salted" is now being applied to plain old "butter".
e.g. I remember about 5 years ago Sainsbury's started calling butter "salted butter", which confused my partner at the time as she just wanted "butter", thinking this was an extra salty butter.
cooking.stackexchange.com/users/37723/Pod
Salt and butter have two very different functions.
Using them together does not allow you to control them separately.
For example, if you need more fat but the dish is already salted, you need butter but not salt.
Therefore, if you want to be as accurate as possible, use unsalted butter.
cooking.stackexchange.com/users/70096/firion
Just a note on all of this - it is not necessarily just about the taste.
A few people have touched on the shelf life, which also makes a difference.
Salted butter is designed to last longer, therefore when doing things like baking - where you want to use the freshest ingredients for a better result - you should always use unsalted, because it will be fresher.
(Especially true when making "challenging" things like pastry).
cooking.stackexchange.com/users/62170/rickibarnes
If it's a recipe for homemade bread they say it's best to use unsalted butter because salt tempers yeast activity, therefore, theoretically, using salted butter would raise salt content (slightly) and possibly lengthen rising time, lessen oven "blooming", and up the finished saltiness of baked bread.
Regardless, I don't find it makes that much difference, for bread baking anyway.
cooking.stackexchange.com/users/70124/Jason
There is no such thing as unsalted butter .
Butter is just made of milk, without salt or any other additive.
If you add salt to it, it becomes salted butter, which is a different thing than butter.
That said, the word "butter" can sometimes refer to salted butter in some countries like the UK.
In countries like France, butter is normally sold unsalted, and salted butter is considered like butter with an additive (salt).
So if the recipe needs butter, just take what is the default in the country of origin of the recipe book.
If you don't know, just take unsalted butter, it's always easier to add salt afterwise than trying to desalt your butter :-).
cooking.stackexchange.com/users/70126/Gabriel Hautclocq
When recipes call for “butter” but doesn’t specify “salted” or “unsalted”, which should I use? Does it matter?
Should I use salted or unsalted butter if the recipe doesn't specify?
cooking.stackexchange.com
<butter>
cooking.stackexchange.com/questions/93163
cooking.stackexchange.com/users/69542/Laila
This depends on the dish being served, but while salted butter can add a balance to the flavour, it gives you less control over the amount of salt you are adding. Generally you should use unsalted butter, but in applications like melting butter on vegetables, salted is usually fine. It is generally considered correct to use unsalted butter in a recipe unless salted is specifically stated. However, this custom may be country-specific. Unsalted butter allows you to control the amount of salt in a dish. Salted butter may be fine in some recipes.
Generally, unsalted butter should be used as it allows the amount of salt in a recipe to be controlled accurately. Salted butter changes the flavour in a dish.  Using salted or unsalted butter depends on the dish. Salted butter melted on some vegetables is fine. Using salted and unsalted butter may be country-specific.