How Often Should You Change an Air Filter?
Filter changes are the cheapest maintenance you can do. How often depends less on the calendar and more on your home.
Last updated:
- Typical
- Every 1–3 months
- Pets or allergies
- Every 30–60 days
- Thick filters
- Often 6–12 months
Most homes should change a standard 1-inch air filter every one to three months. If you have pets, allergies, or heavy dust, change it closer to every 30 days. Thick media filters can last longer, often several months to a year.
What changes the schedule
- Filter type: thin 1-inch filters clog faster than 4-inch media filters.
- Pets: hair and dander load the filter quickly.
- Allergies or asthma: more frequent changes keep the air cleaner.
- Construction, dust, or smoking in the home.
- Run time: a system that runs constantly loads the filter faster.
How to check a filter
- Turn off the system before handling the filter.
- Remove the filter and hold it up to a light. If you cannot see light through it, replace it.
- Note the size printed on the frame so you buy the correct replacement.
- Install it with the airflow arrow pointing in the direction marked on the unit.
Higher MERV is not always better
Very high MERV filters can restrict airflow in some systems. Use a filter rating that matches your equipment and manufacturer recommendations rather than assuming the highest number is best.
Why it matters
A clogged filter makes the system work harder, can raise energy use, and can reduce comfort. It is the least expensive maintenance you can do. For a general routine, see our preventive maintenance guide.
Sources and assumptions
Schedules here reflect common manufacturer and contractor guidance. Always follow your equipment manual for the recommended filter type and interval.
Frequently asked questions
- Can I just clean a disposable air filter?
- No. Standard disposable filters are meant to be replaced, not washed. Some reusable filters can be cleaned, but follow the manufacturer's instructions.
- What happens if I do not change my filter?
- A clogged filter restricts airflow, which makes the system work harder, can raise energy costs, and can lead to comfort problems or frozen coils. It can also shorten equipment life.
- Where is my air filter located?
- It is often at the return air grille, in the blower compartment of the furnace, or in a filter cabinet. Check your system's manual if you cannot find it.