Find Out What Size Furnace Your Home Needs With This Q&A

Many homeowners will get lucky and go years without needing to replace a furnace. That should be the case if you buy a relatively new home since most furnaces are built to last 15-20 years if you maintain the equipment. 

But if your furnace is reaching the end of its life (or already ran out of steam) you’re about to learn more about furnaces than you ever thought you would. One of the first things you need to figure out is what size of furnace you need. 

What works for one house may not work for another even if it’s similarly sized and right next door. There are a lot of factors to consider when you’re balancing performance and energy efficiency. The silver lining is that the best furnace size can be determined by answering a few questions. 

How big is your home?

The single biggest factor for determining the right furnace size is the size of the home. The furnace has to generate enough heat to efficiently warm the home to a comfortable level. 

You can use the square footage of your home to calculate heating needs. By simply multiplying the square footage by the British thermal units per hour (BTUH) factor you determine what size is appropriate. So for a 2,000 square foot home that requires 30 BTUH per square foot you’d need a furnace with 60,000 BTUH capacity or higher.


Furnaces are sized in increments of 20,000 BTUH. The higher the BTUH the larger the furnace is going to be. The majority of furnaces are between 60,000-120,000 BTUH.

Where do you live? 

The recommended heating factor (BTU per square foot) is based on where you live in the U.S. Below are the five U.S. regions and their BTU recommendations:

Zone 1 – 30-35 BTU per square foot (Miami, New Orleans, Houston)

Zone 2 – 35-40 BTU per square foot (Los Angeles, Atlanta, Little Rock)

Zone 3 – 40-45 BTU per square foot (Kansas, Missouri, Virginia)

Zone 4 – 45-50 BTU per square foot (Boston, Chicago, New York)

Zone 5 – 50-60 BTU per square foot (Minneapolis, Buffalo)

Some newer, energy efficient homes can actually stay warm with just 15 BTU per square foot. This is often the case in Zone 1 and Zone 2.

How many people are in your household?

The number of people has an impact on heating needs, but having more people in the home could be beneficial. People generate heat, so having a big family together under one roof could mean your furnace doesn’t have to work as hard.

How many rooms are in the home?

The layout and design of a home matters as well. One large, open room has different heating needs compared to several closed off rooms. Walls create heat loss, so homes with lots of rooms and long hallways will require more BTUH to heat. 

How good is the insulation in your home?

Insulation will affect both the size of the furnace and efficiency. If your home is well insulated you could probably get by with a 15 BTUH per square foot. But if the insulation is lacking you may need to bump it up to 35 BTUH. If you aren’t sure, check it out. It may be more cost effective overall to add insulation. 

Some people are surprised to find the age of the home is really only a factor in terms of its insulation. Newer homes tend to have a good amount of insulation using more efficient materials compared to older homes. 

Does your home have high ceilings?

The higher the ceilings are the more vertical space there is to heat. If your home has vaulted ceilings it’s a good idea to bump up the BTU per square foot measurement. For example, a homeowner in Los Angeles with 12 foot ceilings throughout their home may actually need 45 BTU per square foot rather than 35 BTU.

How many windows does your home have?

The more windows there are in the home the higher the heating factor is going to need to be to compensate for the heat loss. If your home has more windows than average you may need to increase the heating factor by 5-10 BTU per square foot.

Provider Power can supply reliable energy no matter what size your furnace is. Find and compare reliable fixed-rate energy plans in your area!

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