How often to change your furnace filter
Check it every month and replace it at least every three months, per ENERGY STAR. Thin 1-inch fiberglass filters often need changing monthly; pleated filters commonly last 60–90 days; thick media filters can go longer. Change sooner with pets, allergies, or construction dust.
How often to change your furnace filter
Checklist
- Pull the filter and hold it up to a lightMonthly
- Replace it if you can't see light through it, or at the interval for its typeAt least every 3 months
- Write the size (e.g. 16x25x1) somewhere you'll find itOnce
- Buy filters in a multi-pack so you're never outOnce
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| Filter type | Typical change interval |
|---|---|
| 1-inch fiberglass | About every 30 days |
| 1-inch pleated | Every 60–90 days |
| 4–5 inch media | Every 6–12 months (check the label) |
| Home with pets or allergies | Shorten any of the above |
Why it matters
A clogged filter makes the blower work harder. ENERGY STAR notes that a dirty filter can raise energy costs and damage the equipment, leading to early failure.
Filter direction matters: the arrow on the frame points toward the furnace (in the direction the air flows).
What you'll need
- Pleated MERV 8 filters, multi-packThe common 60–90 day filter
- MERV 11 filters (pets or allergies)Catches finer dust; check your system can handle it
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Questions
What happens if I don't change my furnace filter?
Airflow drops, the system runs longer to heat the house, and dust builds up on the blower and coil. Over time that costs more on energy bills and can shorten the life of the equipment.
Is it OK to change the filter more often than recommended?
Yes. Changing it early never hurts the system; it only costs the price of the filter.
Which way does the furnace filter go?
The arrow on the frame points in the direction of airflow, toward the furnace and away from the return duct.
Sources
Related guides
General guidance for typical homes. Follow your equipment manufacturer's instructions and local codes, and hire a pro for anything you're not comfortable doing.