Baseboard heaters are a lowprofile and inexpensive method of adding heat to a home. They can be purchased in a range of sizes to fit the available space, and they do not require any ductwork or expensive retrofitting. As electric heaters, baseboard units are rated in watts. A higherwattage heater will produce more heat more quickly. The amount of wattage you need to heat a room depends on the square footage of the room, the height of the ceiling and the quality of the insulation.

Calculate the square footage of the room you wish to heat by multiplying the room's length by its width.

Measure the height of the ceiling. For every 2 feet above 8 feet, you will need to add 25 percent to the total wattage. For example, a room with 10foot ceilings would require 25 percent more wattage, while a room with 12foot ceilings would need a 50 percent increase.

Determine the quality of your insulation. An average home will require 10 watts per square foot. An older home or one built to less expensive specifications will require 12.5 watts per square foot. A home with aboveaverage insulation (grade R19 wall insulation and R38 ceiling insulation or higher) will require 7.5 watts.

Multiply the square footage of your room by the wattage per square foot determined by your insulation. For example, a 10by10 room with average insulation will require a 1,000 watt heater.

Adjust the total based on ceiling height. For example, a 10by10 room with average insulation and a 10foot ceiling would require a 25 percent increase, or 1,250 watts.
Tips & Warnings
 If you live in a cold climate, with temperatures falling well below freezing for extended periods during winter, purchase the next largest available heater.
 If your calculations fall between two available heaters, purchase the larger of the two.
References
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