No image available
No image available
Your request is being processed.
How Does Microwave Wattage Affect Cooking

How many times have you read the cooking instructions on a container of sweet and sour chicken and wondered whether that little disclaimer about directions being intended for 1100-watt microwaves really mattered?

The simple truth is, watts do matter when it comes to cooking with microwave ovens, because the higher the wattage, the more quickly the oven cooks food. So if you follow the minimum cooking time listed on your sweet and sour chicken package, but cook it in an 800-watt microwave, you might not be cooking your food completely. And that can be a problem.

Finding Your Microwave's Wattage

The easiest way to determine the wattage of your specific microwave oven is to check the little sticker on the inside of the door. You can usually find the wattage listed there with the microwave's serial number and other stats. If that doesn't work, you can always try to locate the owner's manual.

Even if both of these methods prove to be futile, there is still another way to determine the wattage on your appliance. The USDA recommends running a simple "Time-to-Boil Test," which helps you estimate the wattage of your microwave oven.

Time-to-Boil Test: Fill a 2-cup glass measuring cup with 1 cup of water. Stir in ice cubes until the contents are ice cold. Remove any ice still left in the glass and pour out any water exceeding one cup.

Place the measuring glass with one cup of water in your microwave oven, and set it on high for four minutes. Watch the water through the door and note when it starts boiling. Then use the following times to estimate the wattage of your microwave.

  • If the water boils in 2 minutes or less, estimate 1000+ watts.
  • If the water boils between 2 and 2 ½ minutes, estimate about 800 watts.
  • If the water boils between 2 ½ and 3 minutes, estimate about 700 watts.
  • If it takes more than 3 minutes for the water to boil, estimate about 500 watts.


The time-to-boil test illustrates how wattage can affect cooking times. When preparing foods in your microwave, use the minimum recommended cooking time for ovens with high wattage and use the maximum recommended cooking time for ovens with lower wattage.

How Microwave Ovens Work

Microwaves use radio waves at a frequency of about 2,500 megahertz to heat your food. The waves in this frequency are absorbed by fats, sugars and water and converted to heat because of their rapid atomic motion. At the same time, certain types of plastic and glass will not absorb microwaves at this frequency. This explains why microwaves are great for heating foods and why microwave-safe dishes seem to always be made of either plastic or glass.

Remember that partially cooked foods can be dangerous, because bacteria present in the food might not be completely destroyed. Compensate for lower wattage microwave ovens by adjusting the cooking time appropriately. If you are ever in doubt, use a food thermometer to measure the internal temperature of your food.