Furnace filter schedule
How often should you change your furnace filter?
Every 90 days for a standard 1-inch filter, and every 6 to 12 months for a 4-inch or 5-inch media filter. Change it sooner if you have pets, allergies, a remodel underway or wildfire smoke outside.
By filter thickness
| Thickness | Change it | Check it |
|---|---|---|
| 1 inch | Every 90 days | Monthly |
| 2 inch | Every 90 to 120 days | Every 6 weeks |
| 4 inch | Every 6 months | Every 3 months |
| 5 inch | Every 6 to 12 months | Every 3 months |
By household
| Your home | What to do |
|---|---|
| A dog or cat | Change sooner. With a 1-inch filter, many homes with pets land closer to 60 days. |
| Allergies or asthma | Change sooner and consider MERV 11 or 13 if your system handles it. |
| Construction or a remodel | Check every two to three weeks while the work is going on. Drywall dust clogs a filter fast. |
| Wildfire smoke days | In Colorado and across the West that is usually summer into early fall. Check the filter after a smoky week and change it if it has greyed. |
| Vacation home or light use | It can go longer, but change it at least once a year. |
The look test
Hold the filter up to a light. If you cannot see light through the pleats, or the intake side has turned grey, change it, whatever the calendar says.
How to change a furnace filter
About 5 minutes
Turn the system off
Switch the thermostat to off so the blower does not pull dust in while the slot is open.
Find the filter
Check the slot on the furnace, the rack on the duct beside it, and any return grilles in the walls or ceiling.
Note the size and the arrow
Read the size on the edge and see which way the airflow arrow points.
Slide the old one out
Pull it straight out. Bag it so the dust stays in.
Slide the new one in
Point the arrow toward the furnace, in the direction the air flows, and make sure it sits flat with no gap.
Turn the system back on
Set the thermostat back and set your next reminder.
Get a text when it is due
Filterly texts you when it is due and sets the next date when you tap Changed it.