Dried herbs are theoretically more potent and concentrated than fresh. So the general rule is to use a third as much dried as you would fresh, and, conversely, three times as much fresh herb as you would dried.

Fortunately - if the math is a little taxing - the tablespoon and teaspoon are your friends. Since a tablespoon is three times as large as a teaspoon, if you are substituting dried basil for fresh, use one teaspoon for every tablespoon you would have used.

Of course, dried herbs tend to lose potency as they age, so you may need more to get the seasoning you desire. But in general when using herbs and spices, it is in your best interest to season with a light hand. There can be a lot of variation from season to season and among varieties of plants. You can always add more seasoning to a dish, but it is difficult to subtract.