How much dried herb to use when substituting for fresh herbs? When replacing a fresh or leaf herb in a recipe with the dried or powdered kind, what is the ratio I should normally use for the substitution?

E.g. if the recipe calls for 2 teaspoons finely chopped rosemary, how much dried rosemary should I use?
The Cook's Thesaurus is a great resource for these types of conversion and substitutes. There conversions differ for each herb, but for rosemary, they list


  1 tablespoon fresh = 1 teaspoon dried