How to Calculate Furnace Size for Your House? The Tips You Need to Get the Right Furnace

Oct 29, 2022

How to Calculate Furnace Size for Your House? The Tips You Need to Get the Right Furnace

HVAC technicians at homeowners front door

Furnaces come in different sizes. The smallest furnaces may not be able to heat your home, but the largest may be overkill that wastes energy. Choosing the right size furnace is important to prevent cold spots and to keep your home as energy efficient as possible. An HVAC technician can help you size your furnace, or you can consider trying to find the right size yourself, although we suggest that you confirm with a professional before you make your purchase. Here are some tips to figure out how to size your furnace properly.

How to Calculate Furnace Size

You can calculate furnace size using a furnace size chart with some simple math. Essentially you need to know the square footage of your home and then match that to the right number of BTUs. BTUs are British Thermal Units, which is the amount of energy it takes to heat one pound of water one degree Fahrenheit higher. Furnace heat output is measured in BTUs.

Every square foot of your home needs roughly 25-30 BTUs. That means a 1,500 square foot home needs somewhere between 37,500 BTUs and 45,000 BTUs. Although, some things can change that estimation, including layout and climate.

Furnace Size Chart

Here is our furnace size chart:

What Size Furnace Do I Need?

That depends on your square footage. You can use the chart or the calculation above to estimate how many BTUs your furnace needs to be. However, you likely want to confirm this number with your HVAC technician as your home may have different needs than the average home.

How to Tell the BTU of a Furnace

The manufacturer will detail the BTU of your furnace. If you are trying to find out what kind of BTU your current furnace has, you need to figure out the manufacturer and the model, which should be listed on the unit itself. Then you can call the manufacturer and confirm the BTU output. Remember that your model may be slightly different than models by the same name that the manufacturer has now.

We would advise you not to just rely on the current output of your furnace to estimate what you need. It may be that you currently have an undersized furnace that can’t properly serve your home, which ends up causing repairs and early replacement. Or, you may have an oversized furnace that is wasting energy. It’s better to confirm what size furnace you need for yourself than rely on whoever sized it last.

Are you looking to upgrade the furnace for your home and not sure what furnace size is sufficient for your needs? Look no further, call the team at Temp-A-Sure Heating & Air Conditioning today to get the help you need.