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4-Inch Furnace Filters (16x25x4 & 20x25x4)

Four-inch media filters fit a filter cabinet beside the furnace rather than a one-inch slot.

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Four-inch media filters fit a filter cabinet beside the furnace rather than a one-inch slot.

  • Depth varies. Some 4-inch filters measure 3.75 in deep and others about 4.4 in. Honeywell and Aprilaire cabinets take specific replacement models, so match the cabinet or the part number on the old filter.
  • Longer life. The deeper pleats hold more dust; these filters are typically changed every 6 to 12 months.
  • Not interchangeable with 1-inch. A 1-inch slot cannot take a 4-inch filter without a cabinet.

Not sure which rating to buy? See the MERV rating chart and the MERV finder. All sizes: HVAC and furnace air filters.