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Furnace filter sizes

Each size is listed as printed on the frame (nominal). Actual cut dimensions vary by brand and are on the size page. If your label is blank, measure first. Choosing MERV? See MERV 8 vs 11 vs 13.

• 16x25x1Full page. Typical actual ~15.75×24.75×0.75. Common furnace slot.
• 20x20x1Full page. Typical actual ~19.75×19.75×0.75. Common return-grille size.
• 16x20x1Full page. Typical actual ~15.75×19.75×0.75. Same panel as 20x16x1.
• 20x25x1Full page. Typical actual ~19.75×24.75×0.75. Same panel as 25x20x1.
• 14x25x1Full page. Typical actual ~13.75×24.75×0.75. Same panel as 25x14x1.
• 16x24x1Full page. Typical actual ~15.75×23.75×0.75. Same panel as 24x16x1. Not 16x25x1.
• 14x20x1Full page. Typical actual ~13.75×19.75×0.75. Same panel as 20x14x1.
• 18x24x1Full page. Typical actual ~17.81×23.81×0.81. Same panel as 24x18x1. Honeywell does not list this size.
• 16x30x1Full page. Typical actual ~15.81×29.81×0.81. Same panel as 30x16x1. Honeywell does not list this size.
• 20x22x1Full page. Typical actual ~19.81×21.81×0.81. Same panel as 22x20x1. Honeywell does not list this size.
• 12x24x1Full page. Typical actual ~11.75×23.75×0.75. Same panel as 24x12x1.
• 16x25x4Full page. 4-inch media cabinet. Typical Honeywell ~15.94×24.87×4.38. Not 16x25x1 or 16x25x5.
• 20x25x4Full page. 4-inch media cabinet. Typical Honeywell ~19.94×24.88×4.38. Not 20x25x1 or 20x25x5.
• 16x20x4Full page. 4-inch media cabinet. Typical Honeywell ~15.88×19.88×4.38. Not 16x20x1.
• 20x20x4Full page. 4-inch media cabinet. Typical Honeywell ~19.94×19.75×4.38. Not 20x20x1.
• 16x25x2Full page. 2-inch. Typical actual ~15.5×24.5×1.75. Not 16x25x1 or 16x25x4.
• 20x25x2Full page. 2-inch. Typical actual ~19.5×24.5×1.75. Not 20x25x1 or 20x25x4.
• 20x20x2Full page. 2-inch. Typical actual ~19.5×19.5×1.75. Not 20x20x1 or 20x20x4.
• 16x20x2Full page. 2-inch. Typical actual ~15.5×19.5×1.75. Not 16x20x1 or 16x20x4.
• 16x25x5Full page. 5-inch-class media. Typical Honeywell 4-3/8 ~15.75×24.75×4.38. Not 16x25x4. Measure cartridge depth.
• 20x25x5Full page. 5-inch-class media. Typical Honeywell 4-3/8 ~19.88×24.88×4.38. Not 20x25x4. Measure cartridge depth.
• 16x20x5Full page. 5-inch-class media. Typical Honeywell 4-3/8 ~15.88×19.75×4.38. Not 16x20x4.
• 20x20x5Full page. 5-inch-class media. Typical Honeywell 4-3/8 ~19.63×19.88×4.38. Not 20x20x4.
• 20x30x1Full page. Typical Honeywell ~19.5×29.5×0.75. Same panel as 30x20x1. Not 20x25x1.
• 14x30x1Full page. Typical actual ~13.68×29.68×0.81. Same panel as 30x14x1. Honeywell does not list this size.
• 18x20x1Full page. Typical Honeywell ~17.75×19.75×0.75. Same panel as 20x18x1. Not 16x20x1 or 20x20x1.
• 24x24x1Full page. Typical actual ~23.68×23.68×0.81. Honeywell does not list this size. Not 20x20x1.
• 20x24x1Full page. Typical Honeywell ~19.75×23.75×0.75. Same panel as 24x20x1. Not 20x25x1 or 16x24x1.
• 14x24x1Full page. Typical Honeywell ~13.75×23.75×0.75. Same panel as 24x14x1. Not 14x25x1 or 16x24x1.
• 14x14x1Full page. Typical Honeywell ~13.75×13.75×0.75. Square. Not 14x20x1.
• 12x12x1Full page. Typical Honeywell ~11.75×11.75×0.75. Square. Not 12x24x1.
• 16x16x1Full page. Typical Filtrete ~15.81×15.81×0.81. Square. Honeywell does not list. Not 16x20x1.
• 18x18x1Full page. Typical Filtrete ~17.81×17.81×0.81. Square. Honeywell does not list. Not 18x20x1 or 18x24x1.
• 25x25x1Full page. Typical Filtrete ~24.81×24.81×0.81. Square. Honeywell does not list. Not 24x24x1 or 20x25x1.
• 12x20x1Full page. Typical Honeywell ~11.75×19.75×0.75. Same panel as 20x12x1. Not 12x24x1 or 16x20x1.
• 20x23x1Full page. Typical Filtrete ~19.68×22.68×0.81. Same panel as 23x20x1. Honeywell does not list. Odd size, thinner price table. Not 20x24x1 or 20x25x1.
• 16x25x3Full page. Air Bear Cub / Lennox 3-inch. Typical Nordic Pure actual ~15.81×24.31×3. Same panel as 25x16x3. Not 16x25x1, 16x25x2, or 16x25x4.
• 20x20x3Full page. Return-grille cartridge (Honeywell FC40R1003). Typical actual ~19.75×19.75×3. Seats in a 1-inch grille; not a furnace-slot 3-inch pack. Not 20x20x2 or 20x20x4.
• 20x25x3Full page. Return-grille cartridge / top-hat (Honeywell FC40R1011). Typical actual ~19.75×24.75×3. Same panel as 25x20x3. Not a furnace-slot 3-inch pack. Not 20x25x2 or 20x25x4/5.

3-inch pages with published SKUs: 16x25x3 (Air Bear Cub / Lennox), 20x20x3, 20x25x3. Trion Air Bear’s official sheet lists only one 3-inch nominal (16x25x3); other Air Bear sizes are 5-inch. 16x20x3 omitted (no common SKU). Guide: MERV 8 vs 11 vs 13.