The answer is multi-faceted and depends on your living environment, lifestyle, and the air filters you use.
- Fiberglass filters should be replaced every 30 days.
- Pleated air filters and furnace filters should be replaced every 30-60 days (depending on their quality).
- Change your filter every 30 days if someone in your household suffers from allergies or asthma, or if you want better air quality overall.
- If you have pets, you should use a higher MERV, or replace your filter 30 days to deal with odors and sheddings.
- If you have children, it’s best to replace your filter every 30 days for optimum air quality.
In general, it's best to change your air filter every 30 days as this saves on energy because your system isn't overworking to push air through build-ups of dirt. It's important to note that even the thinnest particles of dust can reduce airflow by 50%, so make sure to replace your filter if you can see dust lining your filters.