Dried thyme is equal to one-third fresh thyme. In other words, when you need to replace fresh thyme with dried thyme in a recipe, you need one-third as much of the dried herb. For example, 1 teaspoon of fresh thyme is equal to 1/3 teaspoon of dried thyme.
The flavor concentration is much greater in dried herbs than in comparable fresh herbs, so a smaller amount of the dried herbs is required when cooking. Fresh herbs generally have a better flavor and smell while dried herbs have a much longer storage life. Dried thyme can be stored for up to six months, and fresh thyme can be stored for up to seven days.