Replacement 18x20x1 air filters for homes, offices, and commercial HVAC systems. This collection covers every MERV rating we stock: fiberglass MERV 1–4, pleated MERV 8, MERV 10, MERV 11, and hospital-grade MERV 13.

20+ years in filtration 4.8 from 1,000+ reviews

22 products

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  • 18x20x1 Koch Multi-Pleat XL11 MERV 11 102-091-015 (12 Filters)
    MERV 11
    Koch

    18x20x1 Multi-Pleat XL11 MERV 11

    $189.48
    $189.48
    Case of 12 $15.79/filter
  • 18x20x1 Koch Multi-Pleat XL10 MERV 10 High Capacity 102-121-015 (12 Filters)
    MERV 10 HC
    Koch

    18x20x1 Multi-Pleat XL10 MERV 10 High Capacity

    $186.96
    $186.96
    Case of 12 $15.58/filter
  • 18x20x1 Koch Multi-Pleat XL10 MERV 10 102-111-015 (12 Filters)
    MERV 10
    Koch

    18x20x1 Multi-Pleat XL10 MERV 10

    $157.68
    $157.68
    Case of 12 $13.14/filter
  • 18x20x1 Koch Multi-Pleat XL8 MERV 8 High Capacity 102-031-015 (12 Filters)
    MERV 8 HC
    Koch

    18x20x1 Multi-Pleat XL8 MERV 8 High Capacity

    $169.08
    $169.08
    Case of 12 $14.09/filter
  • MERV Rated Washable Metal Air Filter HVAC
    MERV 8
    RTF

    18x20x1 PrimeShield WashGuard Metal HVAC Air Filter — Washable & Reusable

    $149.99
    $149.99
  • 18x20x1 AAF Flanders PREpleat M13 MERV 13 90013.011820 (12 Filters)
    MERV 13
    AAF Flanders

    18x20x1 PREpleat M13 MERV 13

    $234.99
    $234.99
    Case of 12 $19.58/filter
  • 18x20x1 Exact Filters Pleated MERV 11 (12 pack)
    MERV 11
    Exact Filters

    18x20x1 Pleated MERV 11

    $247.99
    $247.99
    Case of 12 $20.67/filter
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Commercial & facilities

Need 18x20x1 by the pallet?

Volume pricing on any size or MERV, plus recurring delivery schedules. We handle facilities and commercial orders daily and can usually match or beat distributor pricing.

Request a quote 1-866-469-8556 Talk to a filter expert

18x20x1 HVAC, Furnace & AC Filters

Replacement 18x20x1 air filters for homes, offices, and commercial HVAC systems. This collection covers every MERV rating we stock: fiberglass MERV 1–4, pleated MERV 8, MERV 10, MERV 11, and hospital-grade MERV 13. Free shipping on orders over $50.

If your rack is labeled 18x20x1, any filter here will fit. Actual dimensions vary slightly by manufacturer—check the product page for exact specs. Need a non-standard size? Our custom filters cut to 1/8″ precision.

Which MERV Rating Should I Choose?

  • MERV 1–4 (fiberglass) — Lowest cost. Protects your blower and coil from debris but won't improve air quality. Best for rentals and monthly-change schedules.
  • MERV 8 (pleated) — Residential and light-commercial standard. Captures dust, pollen, lint, and mold spores.
  • MERV 10–11 — Captures pet dander, finer particulate, and some bacteria. Recommended for pets, allergies, and facilities pursuing better IAQ.
  • MERV 13 — Hospital-grade. Captures smoke, bacteria, virus carriers, and most airborne allergens. ASHRAE and CDC recommend MERV 13 where the HVAC system can support it.

Not sure? Take our MERV quiz or call 1-866-469-8556.

How Often Should I Change a 18x20x1 Filter?

Plan on every 60–90 days for a 1″ filter in a typical residential or light-commercial system. Homes with pets, smokers, or allergies may need to replace every 30–60 days. Subscribe & save 10% on any filter in this collection.

Why Buy From RememberTheFilter.com

  • Trusted brands — AAF Flanders, Koch, and our own PrimeShield line, built by manufacturers we've partnered with for nearly two decades.
  • Filter Fit Guarantee — if it doesn't fit as expected, we'll make it right.
  • Free shipping over $50 to the lower 48, subscription discounts up to 10%, commercial & bulk pricing available.