Change it every 1–3 months
That's the general rule for a 1-inch filter. Pets, allergies, inversion season and smoke push it toward the short end.
Good to know
Nominal vs actual size
Filters are sold by a rounded nominal size, like 16x25x1. The actual size, often printed smaller on the frame, is usually about half an inch less in width and height, and a 1-inch filter is really about 3/4 inch thick. That gap is on purpose so the filter slides in. If you measure your slot and get 15.5 x 24.5, buy a 16x25.
Picking a MERV rating
- MERV 8: catches dust, lint, pollen and pet hair. A good everyday filter for most homes.
- MERV 11: adds finer dust and more pet dander. A nice step up with pets or mild allergies.
- MERV 13: catches much of the fine smoke and haze particles from inversions and wildfires. Great in a 4–5 inch media cabinet. In a 1-inch slot it can restrict airflow on some systems, so ask before you switch.
- Skip the MERV 14+ “hospital grade” 1-inch filters. They load up fast and can make the furnace run hot or the AC coil freeze.
1-inch vs 4–5 inch media filters
A thick media filter has many times the surface area of a 1-inch filter, so it can filter finer particles without choking airflow, and it lasts months longer. The catch: it needs a media cabinet built for it. You can't stack filters or force a thicker one into a 1-inch slot. Media sizes also vary by brand, so match the part number on the cabinet door.
Questions
Common questions
What does 16x25x1 mean on a furnace filter?
It's the nominal size in inches: 16 inches wide, 25 inches tall and 1 inch thick. The actual filter is usually about half an inch smaller in width and height so it slides into the slot. Buy by the nominal size printed on the frame.
What MERV rating should I use for my furnace?
For most homes, MERV 8 to 11 is the sweet spot. MERV 13 catches finer particles like smoke, but on a 1-inch filter it can choke airflow on some systems. A 4 or 5-inch media filter handles MERV 11 to 13 much more easily.
How often should I change my furnace filter in Utah?
A basic 1-inch filter usually lasts 1 to 3 months. Pets, allergies, a full house, remodeling dust and inversion or wildfire smoke season all shorten that. Thicker 4 to 5-inch media filters often last 6 to 12 months.
Can I put a thicker filter in a 1-inch slot?
No. The filter has to match the slot or cabinet. Going thicker takes a media filter cabinet, which is a simple add-on a technician can install on most furnaces.
Want us to handle the filter?
Ask about our $25 off filter replacement special when we're out for a tune-up or repair, or talk to us about better filtration. Call or text (385) 455-4700.