A stick and slices of butter.
How To Easily Turn Unsalted Butter Into The Salty Variety

If a recipe calls for salted butter, you don't need to make a grocery trip if all you have is unsalted. You can transform unsalted butter into the salted variety that you need.

Start with the addition of ¼ teaspoon of salt per ½ cup of butter. Soften your butter to room temperature so you can incorporate the salt. Taste, and then adjust from there.

If the recipe calls for melted butter, you don't have to wait for it to soften — just melt it on the stovetop or in the microwave and whisk in the salt.

Err on the side of caution so you do not over-salt your food. Taste buds are less perceptive of the flavors of cold foods, so once the butter is warmed up, it will taste saltier.

To fully incorporate the salt, it's best to use some sort of fine-grained salt, like table salt or sea salt.