How to Tell the Wattage of Electric Baseboard Heaters

eHow may earn compensation through affiliate links in this story. Learn more about our affiliate and product review process here.

Things You'll Need

  • Tape measure

  • Screwdriver

  • Calculator

Test the wattage of your baseboard heaters.

Electric baseboard heaters provide additional heating in rooms that may require a little extra boost from your standard heating system. They are also widely used in bathrooms, basements and vestibules as the sole source of heat as these rooms are frequented less than other spaces. It is helpful to know how much wattage an electric heater uses so you can have an idea of how much power you are consuming when running it. You don't want the shock of a very high electric bill from a power-hungry electric heater.


Step 1

Look for a service plate on the electric baseboard heater. If you can find one, it will most likely list the wattage of the heater. If there is no service plate, you will need to estimate the wattage.

Video of the Day

Step 2

Verify the voltage of the electric heater. Open the electric access door on the heater and see how it is wired. If there are two hot wires (black and red) feeding the heater, it is 208 or 240 volts. If there is just one hot (black) wire feeding the heater, it is 120 volts. To determine if its 208 or 240 volts, you will need to find what the rest of your larger appliances are running at. Put the access panel door back into place when finished.

Step 3

Measure the length of your baseboard heater. Estimate the wattage of the heater. For 120 volt and 240 volt heaters, 24 inch long equals 350 watts, 30 inch is 500 watts, 36 inch is 750 watts, 48 inch is 1000 watts and 72 inch is 1500 watts. If running 208 volts the watts is reduced proportionately from 240 volts.


If you are unsure if you are using 208 volts or 240 volts for your baseboard heaters, you may want to consult with an electrician to make that determination.


Be extremely careful when opening the electric access door. If the power is live to the heater, you could get an electric shock touching wires or terminals. Consider turning the power off before venturing into the access door.



Report an Issue

screenshot of the current page

Screenshot loading...