Wattage varies between different models of microwave ovens, from 600 to 1200 watts. Lower-wattage microwaves, because they have less power, do not heat items as quickly as higher-wattage ovens.
They can still cook the same items, but they must be cooked longer to reach the same temperature as a higher-wattage microwave. Generally, small microwaves intended for reheating items rather than regular cooking have a lower wattage.
Larger microwaves intended for everyday cooking tend to have a higher wattage.
High Power Levels
Regardless of wattage or model, most microwave ovens have either 5 or 10 different power levels used to determine the amount and constancy of heat produced. On a 10-level model, the high power levels are 8 through 10.
On a five-level model they are levels 4 and 5. These high power levels produce the most heat.
They are used for cooking beef, pork and poultry, boiling water and reheating foods that have already been cooked.
Medium Power Levels
Medium power levels include 4 through 7 on 10-level models and level 3 on 5-level models. These microwave power levels produce less heat than high levels and more than the lower levels.
Medium power levels are typically about 50 percent cooler than high power levels. They are usually used to cook dairy products, such as cheese, milk or eggs, as well as melt chocolate, heat pudding or bread and cook fish.
Low Power Levels
Low power levels generate the least amount of heat. They generally provide about 25 percent as much heat as the highest heating levels.
These levels are good for defrosting and slow cooking. On 10-level microwave models, low levels are 1 through 3.
On 5-level models, they are 1 and 2. Low levels are typically used to soften butter and cream cheese, slow-roast tough pieces of meat and keep cooked dishes warm.