It’s about 1/4 tsp table/sea salt per 113 g butter, but it can vary. This is usually somewhere around 2 g (a bit under). There’s no reason to worry about it because you can just add salt to taste if it’s something like a flavored butter you’re making. If it’s in baking, shoot for a minimum of 1% salt if it’s cakes and cookies, and 1.5%-2% for bread and savory pastry. A lot of cookies are good with 2% salt, but if you shoot for 1% on a first try due to being unsure, at the very least you won’t find a glaring lack of salt. You’ll also know when to use more based on instinct that comes with experience.
This is in baker’s percentages, btw, so the percentage is based on the weight of the flour.
