How Do You Calculate BTUs for Square Footage?

Heating system requirements vary according to the location of a house.

The strength of the heating system in a building is often measured in British thermal units (BTUs), and determining how many BTUs are necessary for a particular building is an art and a science. A typical house should have a heating system that can muster between 30 and 60 BTUs per square foot of floor space. Builders use systems toward the higher end of the range in the colder regions of the U.S. and they use systems toward the lower end of the range in the warmer regions. So, at best, the calculation of the recommended BTUs for your heating system is an estimate, but it is still worth doing.

Things You'll Need

• Calculator

Instructions

1. Determine the square footage of your house. If you don't already know it, measure the length and width of a single room, in feet, and multiply those measurements. Repeat this for each room in the house and add the results.

2. If your home is located very far north in the U.S., consider using a value of 55 to 60 BTUs per square foot of home. If you are more centrally located but north-leaning, consider using 45 to 55 BTUs per square foot of home. If you are more centrally located but south-leaning, consider using 35 to 45 BTUs per square foot of home. If you are located in the deep south, consider using 30 to 35 BTUs per square foot of home.

3. Calculate the total BTUs your heating system should generate by multiplying your square footage by the BTU range you selected in Step 2. For example, if you live in a 2,000-square foot home in the far north, you will need a heating system in the 55-to-60 BTUs per square foot range.

   Lower BTU estimate = 55 BTUs/ft^2 x 2,000 ft^2 = 110,000 BTUs

   Higher BTU estimate = 60 BTUs/ft^2 x 2,000 ft^2 = 120,000 BTUs

   Your heating system should generate between 110,000 and 120,000 BTUs to adequately heat your home. This is a rough estimate, and you should consult a heating professional to obtain a more definitive number.

References

• AC Direct: How to Size Your System