The wattage on a microwave oven indicates how much electrical power is needed for it to operate. A high wattage on a microwave oven means it cooks food faster than a microwave with a low wattage.
Small or compact microwaves range from 600 to 800 watts, while family-sized microwaves range from 850 to 1,650 watts. Small microwaves are energy efficient, but large microwaves typically cook food quickly. It is important to know the wattage of a microwave to correctly follow food preparation guidelines. Food safety can be compromised if frozen or raw foods are not cooked for long enough. The wattage number is generally found inside the microwave oven's door, on the backside of the microwave or in the instruction manual.
The wattage of a microwave can also be determined by measuring the amount of time needed for it to boil 1 cup of ice-cold water. A high wattage microwave oven over 1,000 watts boils the water in less than 2 minutes. A microwave with an average wattage range of 650 to 700 watts takes 3 minutes to boil the same amount of water.
A high- or low-wattage microwave uses 30 to 80 percent less electricity than a conventional oven, according to the California Energy Commission. Unlike a standard oven, a microwave does not warm up the surrounding area while it cooks, which helps keep cooling costs down and makes it more energy efficient.