How often to change your furnace filter
ENERGY STAR says to check your air filter every month and change it as needed, at least every three months. Thick media filters last longer. AprilAire lists 12 months for its 4 in filters and 12–24 months for its 6 in 201 and 401. Honeywell Home lists up to 1 year and Lennox up to 12 months.
Filter life by type
| Filter | Change it | Who says |
|---|---|---|
| Lower MERV | Possibly every 30 days | Trane |
| Thicker, higher MERV | About every 90 days | Trane |
| Most filters | At least every 90 days; homes with multiple pets “may benefit” from every 30 days | Trane |
| AprilAire TriPure, 1 in and 3 in | Up to 6 months (1 in), up to 12 months (3 in) | AprilAire |
| AprilAire 4 in (210, 213, 410, 413) | 12 months (by model) | AprilAire |
| AprilAire 6 in (201, 401) | 12–24 months; 12 months if the fan runs all day | AprilAire |
| Honeywell Home FC100, FC200 and PopUP | Up to 1 year | Resideo |
| Lennox Healthy Climate box filters | Up to 12 months | Lennox |
What changes the schedule
- Lennox says the number of people in the home, activities, lifestyle, pets and home size all change how often its media needs replacing.
- AprilAire suggests a check every six months if the fan runs all the time.
- Trane says to change the filter year-round, because the furnace moves the air for the AC or heat pump too.
Signs a filter is due
- AprilAire says to replace its filters when they turn from bright white to dark gray.
- If dirt starts to cake on the outside of the filter, AprilAire says to change it right away.
- Some thermostats can show a filter reminder, AprilAire notes. Trane suggests writing the date on the filter edge.
A clean filter keeps the system efficient
ENERGY STAR ties its monthly check to efficiency, so the system “will operate at peak efficiency”. Trane says changing the filter as its dealer directs “can lower energy consumption by 5-15%”.
Some filters are washable
Trane says some systems have washable air filters that can be washed and reused, and others are disposable.
Sources
- ENERGY STAR, Homeowner Manual (2013, PDF): https://www.energystar.gov/sites/default/files/tools/ES_Homeowner_Manual.pdf, accessed 2026-10-28
- ENERGY STAR, Maintenance Checklist (undated page): https://www.energystar.gov/saveathome/heating-cooling/maintenance-checklist, accessed 2026-10-28
- Trane, Furnace Filter Guide (updated 2025-09-08): https://www.trane.com/residential/en/resources/troubleshooting/gas-furnaces/furnace-filter-guide/, accessed 2026-10-28
- Trane, HVAC Air Filters (updated 2025-11-13): https://www.trane.com/residential/en/products/indoor-air-quality/filters/, accessed 2026-10-28
- AprilAire, Air Filter Guide (updated 2026-10-20): https://www.aprilaire.com/whole-house-products/aprilaire-air-filter-guide, accessed 2026-10-28
- AprilAire, Air Purifiers and Air Filters FAQs (updated 2026-03-13): https://www.aprilaire.com/blog/aprilaire-air-purifiers-and-air-filters-faqs, accessed 2026-10-28
- AprilAire filter pages for the 201, 401 and 210 (undated): https://shop.aprilaire.com/products/aprilaire-201-replacement-filter, https://shop.aprilaire.com/products/aprilaire-401-replacement-filter, https://shop.aprilaire.com/products/aprilaire-210-replacement-filter, accessed 2026-10-28
- AprilAire, 213 MERV 13 Air Filter (undated page): https://shop.aprilaire.com/products/aprilaire-213-replacement-filter, accessed 2026-10-27
- Resideo, Honeywell Home Filter Replacement Guide, form 50-1312 (08/20, PDF): https://customer.resideo.com/resources/Techlit/TechLitDocuments/50-0000s/50-1312.pdf, accessed 2026-10-28
- Lennox, Healthy Climate HCC media air cleaners bulletin, form 210450 (August 2025, PDF): https://www.lennox.com/dA/a1d2030a9b/ehb_hcc_2508.pdf, accessed 2026-10-28