Preheat your electric oven to 350 degrees F.
Place an oven-safe thermometer into the oven. The most efficient thermometers for this test have a panel on the outside that you can read without opening the oven door.
Allow the oven to heat up for 30 minutes to give it enough time to reach the target temperature.
Check the thermometer reading through the window in the oven door. If the oven has no window, you will have to open the door, which will make the slightly reading less accurate. In this case, you may want to repeat the procedure a few times and take an average.
Compare the reading on the thermometer to the temperature the stove was set to. If the numbers are the same or only a few degrees off, the thermostat is working properly. If there is more than a few degrees of difference between the numbers, the thermostat is not working properly.