Three whole cloves are equal to 1/4 of a teaspoon of ground cloves. This conversion can be used for any amount of cloves that a recipe calls for.
Most spices are available in both whole and ground versions. Some spices such as cloves are more popular in whole leaf versions. They can also be found in a ground version. Other spices, such as vanilla, are easier to find in a ground or extracted version. A general rule for converting whole leaf herbs and spices to ground herbs and spices is that 1 teaspoon of dried leaves is equal to 1/2 teaspoon of ground herbs. When herbs are fresh and not dried out, only around a third of the amount should be used. For example, if a recipe calls for 1 tablespoon of fresh basil, only 1 teaspoon of dried or ground basil should be used. This difference is because as herbs dry out their flavors become more concentrated. When they are ground, their flavors become even more concentrated. Following these rules for conversion of herbs and spices will ensure that a recipe has the correct amount of flavoring whether fresh, dried or ground herbs and spices are used. Many recipes that require herbs to be in a specific form will state that it should not be substituted.