How to Calculate BTU's

How to Calculate BTU's:

Calculate Square Footage
Measure how many square feet of space you need to heat in your home by measuring the dimensions of each room and hallway. Multiply the length and width of each room to find its square footage, and add them all together for your house's total square footage.

Calculate Furnace Size
Multiply the square footage of your home by a number between 30 and 60 to find the required number of BTUs to heat your home. The exact number you use depends on your climate. Multiply by 30 if you live in an area that rarely gets frost during the winter, multiply by 60 if winter temperatures rarely rise above freezing during the day and choose a number in between for moderate climates