Maintenance ScheduleHVAC filter
How often to change your HVAC or furnace filter
Filter depth sets the base interval. Pets, allergies, building dust and how much the system runs move it.
Your filter
US guidance, in inches and days.
Change it every
60 to 90 days
About 2 to 3 months
Next change
Choose a date
The interval table
These are starting points from the published guidance. A filter that looks grey and matted, or a system that is louder or weaker, means change it now.
| Thickness | Usual interval | With pets or allergies | Source |
|---|---|---|---|
| 1 inch | 60 to 90 days | 30 to 45 days | Filterbuy, ENERGY STAR |
| 2 inches | 60 to 90 days | 30 to 45 days | Filterbuy |
| 4 inches | 6 to 12 months | 4 to 6 months | Filterbuy, Filtrete |
| 5 inches | 6 to 12 months | 4 to 6 months | Filterbuy, Filtrete |
Check monthly, change on the schedule
ENERGY STAR says to check the filter every month, especially in the heating and cooling seasons, and change it at least every 3 months. A dirty filter slows the airflow and makes the system work harder. If it looks dirty after a month, change it then.
The depth of the filter is the biggest factor. A 1-inch panel has a small surface area and clogs quickly. A 4- or 5-inch media filter holds much more dust and can last 6 to 12 months. Filterbuy’s guidance says pets, indoor smoking and renovation dust can roughly halve the interval; allergies and a fan that runs continuously also shorten it. The tool’s adjustments are this site’s rule of thumb from that guidance, not a published figure: pets take the range to 60%, allergies to 75%, and a holiday home stretches it by a quarter.
How to change it
Turn the system off at the thermostat. Slide the filter out and hold it up to the light; if you cannot see light through it, replace it. Match the size printed on the old frame and note the airflow arrow. Write the date on the new frame so the next change is easy to see.
HVAC filter questions
How often should a 1-inch filter be changed?
At least every 3 months, and every month if it looks dirty. A 1-inch filter has little surface area, so it clogs faster than a deep filter.
How often should a 4-inch or 5-inch filter be changed?
Every 6 to 12 months for most homes. Pets, allergies, building work and a fan that runs all day move it towards 6 months.
Do pets really make a difference?
Yes. Filter makers and installers say pets, indoor smoking and renovation dust can roughly halve the interval. When you tick pets, the tool shortens the range to 60% of the usual one, a rule of thumb from that guidance.
What does a holiday home change?
Less use means less dust and fewer hours on the fan, so the filter can last longer. The tool allows a longer range for a holiday home.
Can I use the schedule maker for this?
Yes. Choose Open in the schedule maker and the HVAC filter job is pre-filled with the interval and your last change date. The app can then remind you before the next one.
Sources
The depth table and the monthly check are checked against these sources.
- Heat and cool efficiently. ENERGY STAR (US EPA and DOE).Monthly checks and a three-month minimum for the filter. Checked 6 November 2026.
- Filtrete air filter FAQs. Filtrete (3M).One-inch filters every three months; four-inch and thicker filters annually. Checked 6 November 2026.
- How often to change and replace the HVAC air filter. Filterbuy.The depth table for 1, 2, 4 and 5-inch filters, and shorter intervals with pets. Checked 6 November 2026.