How often you should change your air filters might depend on the following:
- Air filter model
- Overall indoor air quality
- Number of pets
- Household size
- Air pollution levels and construction around the house
For basic 1"–3" air filters, manufacturers often instruct you to replace them every 30–60 days. If you deal with from light to moderate allergies, you could install a better air filter or replace them even more often.
Or, if you're in a more country area or less occupied residence (like a vacation home) and there are fewer cars around, annually could be often enough.
Here are averages that could help you figure out how frequently you should change the air filter at your residence:
- Vacation house or one occupant and no pets or allergies: every 6–12 months
- Ordinary suburban house without pets: every 90 days
- One dog or cat: every 60 days
- More than one pet or if anyone has allergies: 20–45 days