How often should you change your air filter?
- 4 filter types
- Pets and allergies
- Calendar reminders
These are common rules of thumb; your filter's packaging may say otherwise, and it wins. Hold the old filter up to a light: if you can barely see through it, it's done, whatever the calendar says.
Change it
How it works
The schedule starts from the filter's type, since that sets how much dust it can hold, then shortens for your house.
Starting points: 1-inch fiberglass about 30 days, 1-inch pleated about 90, 2-inch pleated about 120, and 4- to 5-inch media about 180.
Pets shorten that: one pet to about 60, 90 or 120 days for the pleated and media filters; two or more to about 45, 60 or 90. Allergies or indoor smoking cap it at the two-pet level. A system that runs most of the day takes off another quarter, and nearby wildfire smoke or construction drops it to about a month (two for media).
These are common rules of thumb from filter makers and HVAC guidance, not a standard, so the packaging on your filter wins. Reminders are generated in your browser as a calendar file.
About this tool
Who it's for
For anyone who's ever pulled out a gray, clogged filter and wondered how long it had been.
Example
You enter1-inch pleated filter, two dogs, system runs most of the day
You getAbout every 34 days, with the next six dates and calendar reminders.
What's different
- Starts from your filter type, not a one-size rule.
- Uses your pets answer from My House and your filter size from the Home Info Sheet.
- Downloads reminders straight to your calendar, no sign-up.
Gotchas and tips
- The filter's own packaging wins over any rule of thumb.
- Hold the old one up to a light; if you can barely see through it, it's done.
- Higher-MERV filters can restrict airflow on some systems; check what yours is rated for.
Privacy: Runs entirely in your browser. Nothing you type is sent to us, and anything it remembers is saved on this device only.
Built and maintained by the GrabTheHammer team, using the same time, cost and safety notes as our guides. Updated November 2026. Spot a problem? Tell us.
Air filter schedule questions
How often should I change a 1-inch pleated filter?
About every 90 days in a typical house, every 60 days with a pet, and every 30 to 45 days with several pets, allergies or heavy use.
Does a thicker filter really last longer?
Yes. A 4- or 5-inch media filter has far more surface area, so it usually lasts 6 to 12 months, though pets and dust shorten that too.
What happens if I don't change it?
A clogged filter cuts airflow, which makes the system run longer, costs more to run, and can freeze an AC coil or overheat a furnace until a safety switch shuts it off.