How Often Should I Change My Furnace Filter?
Answer four quick questions and get a plain-language schedule for checking and changing your filter. No contact details required — the answer shows right here.
The owner does the work himself. We'll look at it in person and give you a price before any work starts.
Request Service
Residential homes only. We'll get back to you during business hours, Monday-Friday 7AM-5PM. Weekend emergency? Call (412) 900-8688. Don't use the form.
Filter thickness and how long it usually lasts
General ranges — not promises. Pets, allergies, and construction dust all shorten these. Always follow the filter maker's label.
| Filter thickness | General change range |
|---|---|
| 1 inch | Every 1–3 months |
| 2 inch | About every 3 months |
| 4–5 inch | About every 6–12 months |
How to find and change your filter
The filter size is printed on the edge of the filter, usually as three numbers like 16x25x1 — width, height, and thickness in inches. The last number is the thickness this tool asks about.
The filter is most often in one of two places: at the furnace itself, in a slot on the side or bottom of the unit, or behind a large return vent on a wall or ceiling. Slide the old one out and read the edge to get the size. Note which way the airflow arrow points before you pull it — the new one goes back in the same way.
When you check it, hold the filter up to a light. If you can't see light through it, change it, no matter what the schedule says. A clean filter keeps air moving and protects your equipment.
Filter questions, answered
Plain answers about filter thickness, how to find your size, and when a problem is more than the filter.