Formula and Assumptions
Replacement interval is shortened for pets, more occupants, allergies, and basic filter types.
Actual conditions, local rates, product labels, and contractor recommendations can change the final quantity or cost.
Example Calculation
A pleated filter in a home with pets may need checking about every 45 days.
Tips
- Check filters monthly.
- Follow HVAC manufacturer guidance.
- Write the install date on the filter.
FAQ
Can I wait until it looks dirty?
No, airflow can suffer before it looks severe.
Do pets matter?
Yes, pet hair and dander shorten filter life.
Do better filters last longer?
Often, but high-MERV filters must match your system.
Does this create reminders?
It gives a recommended interval you can add to your calendar.