How often should I change my furnace filter?

For a 1-inch pleated filter, check monthly and replace every 1-3 months depending on pets and activity. For a 4-inch or 5-inch media cabinet (the thick, pleated cartridge in a steel box), every 6-12 months is typical — they have 4-5x the surface area so they clog more slowly.

Utah-specific reality check: during wildfire-smoke periods (typically July-September on the Wasatch Front), even the best filter will load up much faster. If your filter goes from white to gray in two weeks, that's the smoke, not a bad filter.

MERV 11-13 is the right target for most homes — cleaner air than MERV 8 without the airflow restriction that pushes your blower motor into an early grave.