How to Test Microwave Ovens

Hunker may earn compensation through affiliate links in this story.
You might need to test you microwave oven to make sure it is working properly.
Image Credit: M_a_y_a/iStock/GettyImages

If you are experiencing some issues with your microwave, you may be able to troubleshoot the problem with relative ease. A good place to start is by reviewing your owner's manual. From there, you may be able to figure out what is wrong with the appliance and fix certain issues by testing the microwave.


Why Test a Microwave Oven?

If you are having microwave problems, you can run a series of tests on the appliance to determine what is wrong and how to fix it.

You can test your microwave oven with food. Anything that is prepared or has package instructions is an excellent candidate for this test. Cook the food according to the instructions on the package. For example, if the item should be cooked for five minutes for a 1,200-watt appliance, be sure to do just that.


If the food is not completely cooked after the designated cooking time has elapsed, your oven is not heating adequately. However, if it is overcooked, it's possible that the microwave oven has an issue with its temperature sensor. You can also test the appliance by using the preset cooking time buttons, like the "Popcorn" or "Potato" options. If these do not prepare the given food properly in an allotted cycle, you can assume the microwave is not operating as it should.

Microwave Power Output Formula

If you are questioning whether your microwave is performing at the output it should be capable of as identified by the manufacturer, you can do a series of tests to find out. If you think that your food is undercooked or overcooked, give the microwave power output formula method a try.


JIS Microwave Power Method

According to Celtek, here's how to use the JIS method. Fill two small mugs or glass bowls of water at 68 degrees Fahrenheit or 20 degrees Celsius. Be sure they contain exactly the same amount of water.

Then, measure the temperature of each bowl. Find the average temperature by adding the two figures together and then dividing by two. The temperature will vary slightly, even if you were able to put 68-degree water in the bowls to start, as temperature is subject to change.


Cook the water for one minute in the microwave. When the water is removed, stir it, and then measure the temperature of each again. Find the average temperature of the cooked water. Subtract the average start temperature from the average final temperature and multiply the results by 70. This will yield the power of the microwave oven in watts according to the JIS method.

Boiled Water Method

For an easier water test, place a mug of water in the microwave for 60 seconds at full power. Generally speaking, the water should start to boil around the time your minute of cooking is up. However, this is dependent on several factors, including the material of the mug, the amount of water in the mug and the wattage of the microwave.


If, however, you were to repeat this test several times in a row and find that the microwave was not able to bring your water to a boil, it would likely be an indicator that there was a problem with its heating ability.



Danielle Smyth is a writer and content marketer from upstate New York. She holds a Master of Science in Publishing from Pace University. She owns her own content marketing agency, Wordsmyth Creative Content Marketing (, and she enjoys writing home and DIY articles and blogs for clients in a variety of related industries. She also runs her own lifestyle blog, Sweet Frivolity (

View Work