How often should I change my HVAC filter?

Inspect monthly and set an interval from what you observe. Thin filters typically need attention far sooner than thick pleated media, and pets, dust and heavy run time shorten every interval.

Last reviewed 2026-07-15

Manufacturer intervals assume average conditions. Homes with shedding pets, nearby construction, smokers or continuous fan operation load filters much faster.

The practical test is light: if you cannot see light through the media, airflow is already restricted. Restricted airflow raises energy use and stresses the equipment.

What to check first

Filter size and direction of the airflow arrow
Whether the filter seats without bypass gaps around the frame
That the MERV rating is compatible with your equipment's static pressure limits
Whether you have more than one return filter location

When to call a professional

Airflow remains weak after a fresh filter
The system short-cycles or the indoor coil ices