How Often Should You Change Your HVAC Air Filter?

Changing your air filter is the easiest, cheapest thing you can do for your HVAC system — and the most neglected. A clogged filter is behind a huge share of the breakdowns we see: frozen AC coils, overheating furnaces, weak airflow, and high bills. Here’s everything you need to know.

How often should you change it?

Standard 1-inch filters: every 1–3 months. Check monthly.
Thick 4–5-inch media filters: every 6–12 months.
With pets, allergies, or a dusty home: change more often — monthly is smart.
During heavy use (peak summer or winter): check it more often.

How to tell your filter is dirty

Hold it up to a light — if you can’t see light through it, replace it.
Weaker airflow from the vents than usual.
More dust around the house, or rising energy bills.
The system runs longer or short-cycles.
Ice on the AC (a classic sign of restricted airflow).

How to change your filter (step by step)

Turn off the systemSwitch it off at the thermostat before you start.

Find the filter slotIt’s in the return-air grille (often on a wall or ceiling) or in a slot on the furnace / air handler.

Remove the old filterSlide it out and note the size printed on the cardboard frame (e.g., 16x25x1).

Check the airflow arrowPoint the arrow on the new filter toward the furnace / blower — away from the return grille.

Slide in the new filterInsert it, close the cover, and turn the system back on.

Which filter should you buy?

For most homes, a MERV 8–13 pleated filter is the sweet spot — good filtration without choking airflow. Going higher than your system is designed for can actually restrict airflow and strain the blower, so when in doubt, ask us what’s right for your equipment. Buy the exact size printed on your old filter.

Air Filter Guide — FAQs

How often should I change my furnace or AC filter?

Standard 1-inch filters every 1–3 months (check monthly); thick 4–5-inch media filters every 6–12 months. Change more often with pets, allergies, or heavy use.

What happens if I don’t change my air filter?

A clogged filter restricts airflow, which can freeze your AC coil, overheat and trip your furnace, weaken airflow, raise your bills, and shorten the life of the system.

What MERV rating should I use?

MERV 8–13 works well for most homes — good filtration without straining airflow. Going too high for your system can restrict airflow, so check with us if you’re unsure.