Discriminating bakers and chefs typically use unsalted butter in their recipes because it gives them more control over the salt content and flavor of their dishes. However, sometimes a recipe calls for salted butter, but all you have is unsalted butter. So here's a simple rule of thumb to use so you can make the recipe with unsalted butter. Just remember, for every half cup (1 stick or ¼ lb) of salted butter required, you can add ¼ teaspoon of salt to Challenge Unsalted Butter.
Regular butter contains some salt, and most recipes take this into account.
But if you only have unsalted butter when the recipe calls for regular butter, you can add a ¼ teaspoon of salt for every stick or ½ cup of Challenge Unsalted Butter required.