Whole jeera seeds should be included early in the recipe so the spice has time to release its essence, adding them to a hot broth or oil will allow the aroma and flavors to disperse into the dish. Jeera powder is a quintessential spice in a few different blends, including curry powder. It is also used as part of a rub, in a marinade, and as a seasoning for hearty dishes. So really, it depends on the what kind of recipe are you working with. If switching from whole seeds to ground (or vice versa), you will need to add different amounts. Because the flavor of jeera powder is more concentrated than whole jeera seeds, you will need less in a dish. For a recipe that calls for 1 teaspoon of jeera powder, use 1 1/4 teaspoon of whole jeera seeds.