The power given by a microwave oven can be measured by means of a water heating test. By comparing the test result to the maximum power specified by the manufacturer, it is possible to find out whether the device operates in a normal way. To perform the test, you will need a container for one litre of water, a thermometer and a stopwatch if there is no clock in the microwave oven. Before the test, check the type plate for the maximum power of the microwave oven. The test time is 63 seconds for microwave ovens with maximum power below 1550W and 33 seconds for microwave ovens with maximum power above 1550W.
The test performed under kitchen conditions will give an approximate value. The reliability of the test can be increased by repeating the test at least three times and by calculating a mean value of these results. To obtain an accurate result, the test should be performed in accordance with the standard IEC-705.