The short answer: every 90 days for most homes. Change it every 30 to 60 days if you have pets, allergies, a lot of dust or construction nearby, and check it monthly in the peak of summer and winter.
When to change it sooner
| Your home | Change the filter |
|---|---|
| Vacation home or rarely used | Every 6 to 12 months |
| Typical home, no pets | Every 90 days |
| One dog or cat | Every 60 days |
| Several pets or allergies | Every 30 to 45 days |
| Thin 1-inch filter in peak season | Check monthly |
Thicker filters (4 or 5 inches) usually last 6 to 12 months; the box will say. The quickest test: pull the filter out and hold it up to a light. If you can't see light through it, it's time.
Why it matters
A clogged filter makes the blower work harder, which raises energy bills, strains the motor and can freeze the AC coil in summer. It also stops catching the dust and pet hair it's meant to catch.
Which filter to buy
- Size: it's printed on the edge of the old filter, for example 20x25x1 (width by height by depth in inches). Snap a photo of it.
- Rating: MERV 8 to 11 suits most homes. Higher ratings catch finer particles but can restrict airflow in older systems; check your system's manual before going above MERV 13.
- Buy a few at once. A multi-pack is cheaper and means the next one is already in the closet.
How to change it (5 minutes)
- Turn the thermostat off.
- Open the return grille or the filter slot by the furnace or air handler.
- Slide the old filter out and note which way the airflow arrow points.
- Slide the new one in with the arrow pointing toward the furnace (away from the return).
- Close it up, turn the system back on, and write the date down.
That last step is the one everyone skips. In Tagwell, the filter size, rating and where you buy it are saved with the task, and tapping Done sets the next date for you.
Let Tagwell remember for you
Add this to your home in a tap, get a reminder when it's due, and keep the part details on file. Free to start.