Home

How often should you change an HVAC filter?

Filter depth is the biggest factor. A thin 1-inch panel clogs quickly; a deep 4- or 5-inch media filter holds much more dust. Pets, allergies, building work and a fan that runs all day all shorten the interval.

Check the filter every month and change it at least every 3 months for a 1-inch filter; 4- and 5-inch filters usually last 6 to 12 months.

Range: 1 to 12 months by depth · checked 6 November 2026

Typical interval

What changes it

Depth: 1-inch filters every 1 to 3 months; 2-inch filters every 2 to 3 months; 4- and 5-inch filters every 6 to 12 months.
Pets, allergies or asthma, indoor smoking and building dust can roughly halve the interval.
A full-time home with the fan running continuously will need changes sooner than a holiday home.
A filter that looks grey and matted, or a system that is louder or weaker than usual, means change it now.

Do it

Turn the system off at the thermostat.
Slide the filter out and hold it up to the light; if you cannot see light through it, replace it.
Match the size printed on the old filter’s frame, and note the airflow arrow.
Write the date on the new filter’s frame so the next change is easy to see.

Put it in your schedule

The maker opens with HVAC Filter Change at every 3 months.

No account. The maker keeps the job in your browser and in the link.

Why this interval

The sources below give the full picture. The factors above are the ones that move the interval for most situations.

The range is a starting point, not a rule for every situation. The factors above are the ones the sources name; if your situation is different, use the range and ask a professional where the job needs one.

If you want the job in a schedule with reminders, open the schedule maker with this job already loaded. The how often index has the other jobs.

HVAC Filter Change questions

What changes the interval?

Depth: 1-inch filters every 1 to 3 months; 2-inch filters every 2 to 3 months; 4- and 5-inch filters every 6 to 12 months. Pets, allergies or asthma, indoor smoking and building dust can roughly halve the interval. A full-time home with the fan running continuously will need changes sooner than a holiday home. A filter that looks grey and matted, or a system that is louder or weaker than usual, means change it now.

Does the app use this interval?

The app’s ready-made schedule uses every 3 months. You can change it on the job.

Where does this come from?

The answer is checked against 3 primary sources, linked under Sources with the date each was read.

Sources

The interval and the factors on this page are checked against these sources.

Heat and cool efficiently. ENERGY STAR (US EPA and DOE).Monthly checks and a three-month minimum for the filter. Checked 6 November 2026.
Filtrete air filter FAQs. Filtrete (3M).One-inch filters every three months; four-inch and thicker filters annually. Checked 6 November 2026.
How often to change and replace the HVAC air filter. Filterbuy.The depth table for 1, 2, 4 and 5-inch filters, and shorter intervals with pets. Checked 6 November 2026.