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Clorox 18x20x1 Air Filter MERV 8 Dust & Lint Defense HVAC Furnace Filters, MPR 600 & FPR 5, 4 Count From $35.99

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12 Pack of 18x20x2 MERV 10 Pleated 2" Inch Air Filters by Glasfloss. Actual Size: 17-1/2 x 19-1/2 x 1-3/4 $91.89

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ECO POWER 18x20x1 Air Filter 4 pack, MERV 11 Pleated Furnace & AC Filter, HVAC Replacement Filter for Household Dust & Airborne Particles. $37.99

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Aerostar 18x20x1 MERV 8 Air Filter, Pleated AC Furnace HVAC, Dust Pollen Pet Dander, 4 Pack $28.18 $7.05/count

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100+ bought since yesterday Filtrete 18x20x1 HVAC Furnace Air Filter, MPR 300 MERV 5, Basic Dust and Lint, 1 Filter $5.64

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4.5 out of 5 Stars. 494 reviews
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100+ bought since yesterday Filtrete 18x20x1 HVAC Furnace Air Filter, MPR 800 MERV 10, Micro Particle Reduction, 1 Filter From $11.88

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Best seller Filtrete 18x20x1 HVAC Furnace Air Filter, MPR 1500 MERV 12, Allergens, Bacteria & Viruses, 1 Filter

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Filterbuy 18x20x1 Air Filter MERV 8 Dust Defense, Pleated HVAC AC Furnace Filter Replacement, 4-Pack $34.96

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Aerostar 18x20x1 MERV 8 Air Filter, Pleated AC Furnace HVAC, Dust Pollen Pet Dander, 4 Pack $28.18 $7.05/count

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Best seller Filtrete 18x20x1 HVAC Furnace Air Filter, MPR 1000 MERV 11, Allergens & Pet Dander, 1 Filter From $13.44

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Filterbuy 18x20x1 Air Filter MERV 8 Dust Defense, Pleated HVAC AC Furnace Filter Replacement, 4-Pack $34.96

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AMI PARTS 18x20x1 HVAC Furnace Air Filter MERV 8 for Dust Reduction,4 Filters $27.99

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Best seller Air-Care 18x20x1 Forever Filter, Allergen & Dust Reduction, Permanent Washable Electrostatic HVAC Furnace Air Filter, MERV 8

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AMI PARTS 18X20X1 Furnace Air Filter MERV8 HVAC ,Air Filter for Allergen, Bacteria and Virus,6 Filters $36.99

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4.8 out of 5 Stars. 5 reviews
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Best seller Simply Filters 18x20x1 MERV 8, MPR 600, AC Furnace HVAC Air Filter (6 Pack) From $27.25

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Filterbuy 18x20x1 MERV 11 Allergen Defense, Pleated HVAC AC Furnace Air Filters (1-Pack) $15.00 $15.00/in

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PuroAir Mega Filter - MERV 13 18x20x1 Air Filters with Carbon From $24.99

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4.6 out of 5 Stars. 31 reviews
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Aerostar 18x20x1 MERV 8 Air Filter, Pleated AC Furnace HVAC, Dust Pollen Pet Dander, 6 Pack $32.26 $5.38/count

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Aerostar 18x20x1 MERV 8 Air Filter, Pleated AC Furnace HVAC, Dust Pollen Pet Dander, 6 Pack

4.7 out of 5 Stars. 58 reviews

18 in. x 20 in. x 1 in. Superior Pleated Air Filter FPR 9, MERV 12 ( 1 Pack) $19.99

18 in. x 20 in. x 1 in. Superior Pleated Air Filter FPR 9, MERV 12 ( 1 Pack)
current price $19.99

18 in. x 20 in. x 1 in. Superior Pleated Air Filter FPR 9, MERV 12 ( 1 Pack)

3 out of 5 Stars. 3 reviews
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Filterbuy 18x20x1 Air Filter MERV 13 Smoke Defense, Pleated HVAC AC Furnace Filter Replacement, 6-Pack $57.96

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Filterbuy 18x20x1 Air Filter MERV 11 Allergy Defense, Pleated HVAC AC Furnace Filter Replacement, 6-Pack $45.96

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Cabana Air Filters Furnace Air Filter - Merv 13 - 6 Pack, 18 x 20 x 1 From $34.99

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4.7 out of 5 Stars. 34 reviews
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Filter King 18x20x1 Air Filter | 3-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75" $36.63

Filter King 18x20x1 Air Filter | 3-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75"
current price $36.63

Filter King 18x20x1 Air Filter | 3-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75"

4.6 out of 5 Stars. 48 reviews

Filtrete 18x20x1 HVAC Furnace Air Filter, MPR 700 MERV 8, Dust, Pollen & Pet Dander Reduction, 2 Pack From $22.85

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4.7 out of 5 Stars. 9 reviews
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Simply Filters 18x20x1 MERV 11, MPR 1000, AC Furnace HVAC Air Filter (2 Pack) From $29.97

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4 out of 5 Stars. 1 reviews

Best seller (4 pack) Filtrete 18x20x1 HVAC Furnace Air Filter, MPR 1500 MERV 12, Allergens, Bacteria & Viruses, 1 Filter $73.88 $18.47/ea

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(4 pack) Filtrete 18x20x1 HVAC Furnace Air Filter, MPR 1500 MERV 12, Allergens, Bacteria & Viruses, 1 Filter

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Aerostar 18x20x1 MERV 11 Air Filter, Pleated AC Furnace HVAC, Pet Dander Mold Smoke, 4 Pack $38.73 $9.68/count

Aerostar 18x20x1 MERV 11 Air Filter, Pleated AC Furnace HVAC, Pet Dander Mold Smoke, 4 Pack
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4.2 out of 5 Stars. 5 reviews

ECO POWER 18x20x1 Air Filter 4 pack, MERV 11 Pleated Furnace & AC Filter, HVAC Replacement Filter for Household Dust & Airborne Particles. $37.99

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Filter King 18x20x1 Air Filter | 4-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75" $34.28

Filter King 18x20x1 Air Filter | 4-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75"
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Filter King 18x20x1 Air Filter | 4-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75"

4.7 out of 5 Stars. 45 reviews

Filterbuy 18x20x1 Air Filter MERV 11 Allergy Defense, Pleated HVAC AC Furnace Filter Replacement, 4-Pack $39.96

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Filterbuy 18x20x1 Air Filter MERV 13 Smoke Defense, Pleated HVAC AC Furnace Filter Replacement, 4-Pack $49.96

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Clorox 18x20x1 Air Filter MERV 13 Virus & Bacteria Defense HVAC Furnace Filters, MPR 1900-2200 & FPR 9-10, 4 Count From $35.99

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4.8 out of 5 Stars. 5 reviews

Protect Plus Air 118201 Fiberglass Air Filter, 18" X 20" X 1" (Pack of 12) $50.98

Protect Plus Air 118201 Fiberglass Air Filter, 18" X 20" X 1" (Pack of 12)
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1 out of 5 Stars. 1 reviews

Filter King 18x20x1 Air Filter | 6-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75" $32.34 Was $39.90

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Filter King 18x20x1 Air Filter | 6-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75"

4.7 out of 5 Stars. 37 reviews

Cabana Air Filters Furnace Air Filter - MERV 11 - 6 Pack, 18 x 20 x 1 From $37.99

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4.9 out of 5 Stars. 34 reviews
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Nordic Pure 18x20x2 Pleated MERV 13 Air Filters 12 Pack From $52.49

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Aerostar 18x20x1 MERV 13 Air Filter, Pleated AC Furnace HVAC, Smoke Bacteria Allergy, 4 Pack $43.96 $7.33/count

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4.5 out of 5 Stars. 35 reviews

PureFlow, Home Furnace Air Filter 18x20x1, with 4 Layers of Advanced Filtration Technology, MERV-13 Pack-of-2 From $38.95

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AAF Flanders EZ-Flow II 18X20X1 Flat Panel Furnace Air Filter MERV 1, 1 Filter $53.32

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Aerostar 18x20x4 MERV 13 Air Filter, Pleated AC Furnace HVAC, Smoke Bacteria Allergy, 6 Pack $213.36

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Filterbuy 18x20x1 Air Filter MERV 8 Dust Defense, Pleated HVAC AC Furnace Filter Replacement, 3-Pack $33.99

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Filter King 18x20x0.5 Air Filter | 4-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x 0.5" $91.84

Filter King 18x20x0.5 Air Filter | 4-PACK | MERV 8 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x 0.5"
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Filterbuy 18x20x1 Air Filter MERV 11 Allergy Defense, Pleated HVAC AC Furnace Filter Replacement, 6-Pack $45.96

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Filter King 18x20x1 Air Filter | 4-PACK | MERV 13 HVAC Pleated A/C Furnace Filters | MADE IN USA | Actual Size: 17.5 x 19.5 x .75" $48.96

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Airflux Filters Fiberglass Furnace Filters, 18x20x1, for Dust, 12 Pack From $56.94

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Filterbuy 18x20x2 Air Filter MERV 11 Allergy Defense, Pleated HVAC AC Furnace Filter Replacement, 2-Pack $41.98

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3 Pack of 18x20x2 MERV 10 Pleated 2" Inch Air Filters by Glasfloss. Actual Size: 17-1/2 x 19-1/2 x 1-3/4 $38.95

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5 out of 5 Stars. 1 reviews

Simply Filters 18x20x1 MERV 8, MPR 600, AC Furnace HVAC Air Filter (4 Pack) From $26.60

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4.6 out of 5 Stars. 599 reviews

Air-Care 18x20 Electrostatic Flexible Permanent Washable HVAC Furnace Filter, MERV 8 $44.95

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Highly rated by customers

FAQ

Why is an 18x20x1 not exactly 18x20 inches?

Most HVAC filters list a nominal size (like 18x20x1) that’s rounded for easy shopping. The actual size is often slightly smaller so it fits into the slot or grille. For example, many 18x20x1 filters measure about 17.5" x 19.5" x 0.75".

  • Check your current filter: Measure length, width, and thickness and note both nominal and actual sizes printed on the frame.
  • Review product details: Product pages list the actual size—match that to your opening if tolerances are tight.
  • Aim for a snug fit: Avoid gaps that let air bypass the filter. Don’t force a too-large filter.

You can compare actual sizes online and choose pickup or delivery for convenience.

18x20x1 vs 18x20x2, what’s the real difference?

The main difference is thickness and the amount of filter media. An 18x20x2 filter typically has more pleats than a 1-inch version, which can help with airflow and service life at a similar MERV rating, though results vary by system.

  • Compatibility: Only use a 2-inch filter if your furnace/return grille is designed for it.
  • Performance: More media can reduce pressure drop compared to thinner filters of equal rating, but this depends on the product and your HVAC.
  • Do not stack: Avoid stacking two 1-inch filters to mimic a 2-inch filter.

Check your unit’s manual and the filter slot depth before choosing; then select the thickness that fits your setup.

Which MERV rating should I choose for my home?

MERV indicates how well a filter captures particles. Choosing a rating is about balancing filtration and airflow that your system can handle.

  • MERV 5–8: Basic dust and lint—good for general protection.
  • MERV 9–11: Better capture of pollen and pet dander for many homes.
  • MERV 12–13: Finer particles, including smoke and smaller aerosols.

Higher MERV filters can be more restrictive, which may affect some HVAC systems. It’s a good idea to check your equipment manual or consult a technician before moving up in rating. Also, some packages use alternative rating scales—look for the listed MERV equivalent on the packaging to compare apples to apples.

How do I clean a reusable 18x20 HVAC filter?

Reusable filters are designed to be washed and reinstalled, following the manufacturer’s directions.

  1. Turn off your system and remove the filter.
  2. Rinse both sides with gentle water flow; use mild soap only if the maker allows.
  3. Air-dry completely before reinstalling. Some models note machine-wash or dryer-safe on the label—follow only what your specific filter states.
  4. Reinstall with the airflow arrow pointing the right direction.

Tip: Inspect monthly and clean when visibly dirty. Many reusable options are rated around MERV 8, while higher-MERV disposable filters are also available if you need finer filtration. Choose the approach that fits your air quality goals and HVAC recommendations.

Which way should the airflow arrow face when installing?

Use the arrow printed on the filter’s frame as your guide—it shows the direction of airflow.

  • At a return grille: Arrow should point into the duct or wall.
  • At the furnace/air handler: Arrow should point toward the equipment (toward the blower).
  • Fit matters: Ensure the filter sits snugly with no gaps along the edges.
  • Close panels securely: Replace the grille or furnace door before turning the system back on.

Mark the install date on the frame to help track changes. If your setup is unusual, checking your HVAC manual can help confirm orientation for your specific system.

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