Well, that depends. Microwaves are rated by wattage (our Panasonic is rated at 1250W). Higher wattage means more energy per minute, but it cooks faster than lower wattage models. All things being equal, they probably all use about the same energy to cook a given products (e.g., 1250 for 1 minute versus 675 for 2 minutes). Compared to other cooking methods, microwaves are thought to be VERY energy efficient. No preheating, little wasted energy (e.g., heat loss), etc. The main gripe people have is that they don't brown the food, so if you care, you would need to look for a combination microwave/convection model...typically more expensive and less efficient. Microwaves are efficient, convenient, and FAST! Best for re-heating, defrosting, and cooking snacks and small meals. We use it more that any other method, and save the stove and ovens for things that are best cooked that way (roasting turkeys, baking, large meals, etc.).