How Often Should You Change Your Air Filter? (By Household Type)
The boxes say "up to 90 days." The truth depends on your house. Here are the schedules our techs actually recommend, based on what we pull out of furnaces across western Kentucky every week.
Replacement schedule by household
| Your household | 1-inch filters | 4-5″ media filters |
|---|---|---|
| No pets, no allergies, 1-2 people | Every 90 days | Every 12 months |
| One pet, or light allergies | Every 60 days | Every 9-12 months |
| Multiple pets, kids, or real allergies | Every 30 days | Every 6-9 months |
| Smokers, wood stove, remodel dust, or wildfire season | Every 30 days | Every 6 months |
What happens when you forget
A clogged filter is not a cosmetic problem. In order of what we see in the field:
- Airflow drops and rooms get uneven. The far bedrooms stop getting cool air first.
- Energy use climbs. The blower works harder against the clog, which can raise your energy bill.
- The evaporator coil can freeze. Restricted airflow over the coil in cooling season causes ice-ups, one of the most common "my AC stopped cooling" service calls we run in July.
- Blower motors die young. Motors are cooled by the air moving through them. That is how years of clogged filters turn a cheap filter habit into an expensive motor replacement.
Two ways to never forget
The free way: change it when your utility bill arrives, or set a phone reminder for the first of the month and check it. If you can't see light through it, change it.
The stocked-up way: keep a case in the closet. A case of 12 is a year of filters for a home that changes one a month, so the next filter is always on hand. Our Filter Club yearly subscription sends a new case every 12 months at the same price, and you can cancel any time by phone or email.
Does a higher MERV change the schedule?
Yes, slightly. Higher-MERV filters capture more, so they load faster. Our MERV comparison guide covers it, but the short version: whatever the rating, a filter changed on time beats a better filter changed late.