How Often Should I Change My Furnace Filter?

February 5, 2020

Dirty Furnace FilterUnfortunately, there’s no one rule for how often to change your furnace’s filter as a number of factors are at play. Some people need to change theirs monthly while other people can change it every six months. Here are some of the issues that determine how often you should change yours.

Size of Your Filter

Smaller filters need to be changed more often. A 1-inch or 2-inch filter needs to be changed every three months. A 4-inch filter should last six months, while a 5-inch filter can last for a year.

A visibly dirty filter is a sign it needs to be replaced. If your heating system is running all the time, a likely culprit is a dirty air filter. If your home has more dust than normal, that’s another sign you need a filter change.


Homes with pets need to change the furnace filter more often, especially if one of the occupants is allergic to them. A home with a single dog or cat should change the filter about twice as often. More pets can mean changing the filter monthly.


Smoking does a number on your home’s environment. This includes dramatically shortening how often a filter will last unless they limit themselves to smoking outdoors. Your furnace filter will turn a sickly shade once it accumulates enough cigarette smoke, indicating it needs to be replaced.

At Air Patrol Air Conditioning, Heating & Fireplaces of Dallas/Fort Worth, we help customers with all of their HVAC needs, including filter replacement. We provide regular maintenance, which includes inspecting and replacing the filter.

You Have a Larger Home

Larger homes have exponentially more air in them than smaller homes. This means the central furnace filter will need to be replaced more often in relation to your home’s increased square footage.

We Solve Your HVAC Problems

Air Patrol Air Conditioning, Heating & Fireplaces has been helping customers since 2003. We offer services for air conditioners, furnaces, fireplaces, indoor air quality, and whole-home audits. We take a whole-house performance approach to help save you money. Please contact us today to find out how we can address your needs.