Furnace Filters
Best 18x18x1 Furnace Filter (2026): Our 5 Picks Ranked
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For an 18x18x1 furnace filter, the Filtrete leads this list: it pairs MERV 11 with MPR 1000 in a 4-pack for 90-day changes. The Aerostar adds MERV 13 with MPR 1500 in a 6-pack, while the Simply and UBeesize offer MERV 8 and the Flanders covers basic filtration at MERV 4.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallFiltrete 18x18x1 Air Filter9.8 View on Amazon -
Runner-UpSimply 18x18x1 Air Filter9.5 View on Amazon -
Also GreatAerostar Air Filter 18x18x1 MERV 13 AC9.4 View on Amazon -
9.4 View on Amazon -
Also GreatFlanders Air Filter E-Z Flow II9.2 View on Amazon
Compare the specs
Ranked on pack size from each listing, plus how many buyers have rated it. A dash (—) means we could not confirm that figure from the listing.
| Pick | MERV rating | Pack size | Weight | Warranty |
|---|---|---|---|---|
| 1. Filtrete 18x18x1 Air Filter | MERV 11 | 4-pack | — | — |
| 2. Simply 18x18x1 Air Filter | MERV 8 | 12-pack | — | — |
| 3. Aerostar Air Filter 18x18x1 MERV 13 AC | MERV 13 | 6-pack | — | — |
| 4. UBeesize 18x18x1 Reusable Electrostatic Air Filter HVAC | MERV 8 | — | — | 2-year |
| 5. Flanders Air Filter E-Z Flow II | MERV 4 | — | — | — |
Filtrete 18x18x1 Air Filter
It pairs MERV 11 with MPR 1000 in a 4-pack, with pleated media and a 90-day change interval.
- MERV rating: MERV 11
- Pack size: 4-pack
Good for
- Buyers who want MERV 11 filtration
- Buyers who want a 4-pack
Skip it if
- You want MERV 13 filtration
- You want a 12-pack
It has MERV 11 with 1000 MPR in a 4-pack of pleated filters, and the actual size is 17.68 by 17.68 by 0.81 inches. Change the filter at least once every 90 days.
Simply 18x18x1 Air Filter
It pairs MERV 8 with a 12-pack of pleated filters, with an actual size of 17.75 by 17.75 by 0.75 inches.
- MERV rating: MERV 8
- Pack size: 12-pack
Good for
- Buyers who want MERV 8 filtration
- Buyers who want a 12-pack
Skip it if
- You want MERV 11 filtration
- You want a 4-pack
It has MERV 8 in a 12-pack, with electrostatically charged synthetic pleated media. The filters last up to 3 months, and the actual size is 17.75 by 17.75 by 0.75 inches.
Aerostar Air Filter 18x18x1 MERV 13 AC
It pairs MERV 13 with MPR 1500 in a 6-pack, with synthetic electrostatic media.
- MERV rating: MERV 13
- Pack size: 6-pack
Good for
- Buyers who want MERV 13 filtration
- Buyers who want a 6-pack
Skip it if
- You want MERV 8 filtration
- You want a 12-pack
It has MERV 13 with MPR 1500 in a 6-pack, with 100% synthetic electrostatic media for low air flow resistance. Change the filters every 60 to 90 days.
UBeesize 18x18x1 Reusable Electrostatic Air Filter HVAC
It pairs MERV 8 with a reusable washable design, an aluminum frame and a 2-year warranty.
- MERV rating: MERV 8
- 2-year warranty stated
Good for
- Buyers who want a reusable filter
- Buyers who want a 2-year warranty
Skip it if
- You want MERV 13 filtration
- You want a 12-pack of filters
It has MERV 8 in a reusable electrostatic filter with an aluminum frame and pleated layers. Wash it with water and a little detergent, clean it every 3 months, and it carries a 2-year warranty.
Flanders Air Filter E-Z Flow II
It pairs MERV 4 with a 12-pack of flat panel fiberglass filters for 30-day changes.
- MERV rating: MERV 4
Good for
- Buyers who want MERV 4 filtration
- Buyers who want a 12-pack
Skip it if
- You want MERV 8 filtration
- You want a change interval past 30 days
It has MERV 4 in a 12-pack of flat panel filters made from spun fiberglass. It captures dust and lint, fits standard 18 by 18 by 1 slots, and replacement comes every 30 days.
How to choose
MERV figures and pack sizes
MERV figures run from 4 on the Flanders to 8 on the Simply and UBeesize, 11 on the Filtrete and 13 on the Aerostar. Pack sizes run from 4 on the Filtrete to 6 on the Aerostar and 12 on the Simply and Flanders, and the UBeesize is a reusable filter. A higher MERV number means finer particle capture, so compare the MERV figure and the pack with your replacement schedule.
Change intervals and upkeep
Change intervals run from 30 days on the Flanders to 60 to 90 days on the Aerostar, 90 days on the Filtrete, up to 3 months on the Simply, and cleaning every 3 months on the UBeesize. The UBeesize washes with water and a little detergent, while the others are replaced when the interval ends. Pick the interval that fits your replacement schedule.
Media types and sizes
Media types differ: the Filtrete uses pleated polypropylene, the Simply uses electrostatically charged synthetic pleated media, the Aerostar uses synthetic electrostatic media, the UBeesize uses pleated layers on an aluminum frame, and the Flanders uses spun fiberglass in a flat panel. All five fit nominal 18 by 18 by 1 slots, so check the actual size on the pick you choose.
FAQ
What MERV figures do these filters have?
The Aerostar has MERV 13, the Filtrete has MERV 11, the Simply and UBeesize have MERV 8, and the Flanders has MERV 4.
Which filters come in a 12-pack?
The Simply and Flanders come in 12-packs. The Filtrete comes in a 4-pack, and the Aerostar comes in a 6-pack.
Which filter is reusable?
The UBeesize is reusable and washable: wash it with water and a little detergent, and clean it every 3 months.
When should each filter be changed?
The Flanders is replaced every 30 days, the Aerostar every 60 to 90 days, the Filtrete every 90 days, and the Simply lasts up to 3 months.
