Converting milligrams to teaspoons

I am trying to convince my dad that he needs to give up some, not all, of his snack products because they are so high in salt, which he is supposed to be watching. I tried to find a table that will convert milligrams to teaspoons, but didn't have any immediate luck (although I will admit I didn't look that long, either). I might be able to figure this out myself given enough time. However, since the point is to keep my dad from killing himself within the next ___ years a little help would probably be good. Math has never been my thing. I always have to do it the slow, tedious way. It's disgusting. Thanks for your help.