# How Often Should You Replace an Air Purifier Filter? _Last updated: 2026-09-26_ ## Short answer Rinse or vacuum a washable pre-filter monthly. Replace the HEPA cartridge every 6 to 12 months in a normal home, and every 3 to 6 months with pets, smoke or construction dust. Replace the carbon layer whenever odors return, which is often sooner than the HEPA interval. ## What shortens filter life - Pets: hair and dander load the pre-filter and cartridge quickly. - Smoke and candles: fine particles and odor load both HEPA and carbon. - Construction, renovation or wildfire smoke nearby. - Running the unit on high speed 24/7. - A clogged pre-filter, which pushes everything into the HEPA. ## Signs it is time - Airflow at your usual speed feels weaker. - The filter is visibly grey, dark or matted with hair. - Odors return even at high speed (carbon is spent). - The auto mode runs higher than it used to. - A musty smell from the outlet. ## How to check and replace 1. Unplug the unit and open the filter cover. 2. Inspect the pre-filter: rinse or vacuum it, and let it dry fully before refitting. 3. Note the cartridge date and check it against the manual's interval. 4. Replace the cartridge when airflow or odor tells you it is due, not only on the calendar. 5. Reset the filter indicator if the unit has one. 6. Vacuum the intake and the housing before fitting the new filter. ## Plan the cost Filters, not electricity, are the main running cost. Multiply the cartridge price by how many you expect to use per year (one or two in a normal home, two to four with pets) and check that replacements stay in stock for your model. ## Sources Manufacturer filter-replacement intervals for your model; U.S. EPA, Guide to Air Cleaners in the Home, for how particle and carbon filtration load over time. ## Frequently asked questions **Q: Can I wash a HEPA filter?** A: No. True HEPA media is not washable; washing damages the fibers. Only wash a pre-filter that the manual says is washable, and let it dry before use. **Q: Do I count from purchase or from first use?** A: Count from first use. A unit that sat in a box has not loaded its filter, so start the interval when you begin running it. **Q: Why does my filter last less than a year?** A: Pets, smoke, high run speed and a dirty pre-filter all shorten filter life. Check the pre-filter monthly and expect a shorter HEPA interval in a busy home. ## Recommended options Filter availability and cost vary by model, so check that replacements are easy to buy before choosing a unit. - [DREO 530S Air Purifier (RGBIC)](https://www.amazon.com/dp/B0H8SB7YY1?maas=maas_adg_api_585602613512925350_static_12_201&ref_=aa_maas&tag=maas&aa_campaignid=PBd80bd4ce4ece40f44bcc76fcc0c48425&aa_adgroupid=99abOnP1pC8lf4AnvobrGKTnTfr_aKBQUZzDSUkZjocNFub_bs2frgjcI9NkRYC5C65ukTVHJxDAMQFHWlCkIH&aa_creativeid=8f82wlDYPds5P7ntLZtXI09xBlRY0rvWPPQ0azuMhEvyCLc_c) — DREO, rating 4.5/5 (555 reviews) - [DREO DR-HAP009AS Pet Air Purifier](https://www.amazon.com/dp/B0H753GWC1?maas=maas_adg_api_585602613512925350_static_12_201&ref_=aa_maas&tag=maas&aa_campaignid=PBd80bd4ce4ece40f44bcc76fcc0c48425&aa_adgroupid=13ecG5KAMWcfJykf4pdfWcStqvzCgeCvqzsR_bcnGq2HJTblNA9W1GA6P7kEDkbx8ClHvhIZxYW6xXmBzqJL0&aa_creativeid=fff7QUdtMLEX_a2n4hsK10QP49ZRFN6OipmXUkpgLBAnLg9w_c) — DREO, rating 4.5/5 (555 reviews) _Some links on this page are affiliate links. We may earn a commission at no additional cost to you._ --- Canonical: