Furnace Filters
Best 12x20 Furnace Filter (2026): 4 Models Side by Side
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For a 12x20 furnace filter, the Filter King 12x20x1 leads this list as a 6-pack of MERV 8 pleated filters with an actual size of 11.5 x 19.5 x .75 inches. The Filtrete 12x20x1 follows with a MERV 13 rating and MPR 1900 in a 2-pack, while the Simply 12x20x1 offers MERV 11 in a 6-pack and the Flanders pack holds 12 fiberglass filters.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallFilter King 12x20x1 Air Filter MERV9.8 View on Amazon -
Runner-UpFiltrete 12x20x1 Air Filter9.7 View on Amazon -
Also GreatSimply 12x20x1 Air Filter9.4 View on Amazon -
Most in the PackFlanders/Precisionaire 12x20x1 Fiberglass Furnace Filters9.2 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. Filter King 12x20x1 Air Filter MERV | MERV 8 | 6-pack | — | — |
| 2. Filtrete 12x20x1 Air Filter | MERV 13 | 2-pack | — | — |
| 3. Simply 12x20x1 Air Filter | MERV 11 | 6-pack | — | — |
| 4. Flanders/Precisionaire 12x20x1 Fiberglass Furnace Filters | — | 12-pack | — | — |
Filter King 12x20x1 Air Filter MERV
A 6-pack of MERV 8 pleated 12x20x1 filters with an actual size of 11.5 x 19.5 x .75 inches, lasting up to 90 days.
- MERV rating: MERV 8
- Pack size: 6-pack
Good for
- Buyers who want a 6-pack of MERV 8 filters
- Owners of 12x20x1 slots who change filters every 30 to 90 days
Skip it if
- You need a MERV rating above 8
- You want fewer than 6 filters in a pack
The filters measure 12 x 20 x 1 inches, with an actual size of 11.5 x 19.5 x .75 inches. The pleated design is built to trap airborne particles without impacting air flow, and the maker recommends changing 1 inch filters every 30 to 90 days, with filters lasting up to 90 days. Installation is open, slide and close.
Filtrete 12x20x1 Air Filter
A 2-pack of MERV 13, MPR 1900 pleated filters in 12x20x1, with Filtrete 3-in-1 technology and a change interval of 90 days.
- MERV rating: MERV 13
- Pack size: 2-pack
Good for
- Buyers who want a MERV 13 filter with MPR 1900
- Buyers who want app reminders for filter changes
Skip it if
- You need a MERV rating above 13
- You want more than 2 filters in a pack
The filters measure 12x20x1, with an actual size of 11.81 x 19.81 x 0.78 inches, and carry a MERV 13 rating with MPR 1900. Filtrete 3-in-1 technology pulls in and traps unwanted particles, and the filters are designed for furnaces, air conditioners and heating systems or HVAC systems. The Filtrete Smart App sets 30-, 60- or 90-day reminders, and the maker recommends changing the filter at least once every 90 days. A limited warranty applies.
Simply 12x20x1 Air Filter
A 6-pack of MERV 11 pleated 12x20x1 filters with an actual size of 11.75 x 19.75 x 0.75 inches, lasting up to 3 months.
- MERV rating: MERV 11
- Pack size: 6-pack
Good for
- Buyers who want a 6-pack of MERV 11 filters
- Owners who want up to 3 months of filtration
Skip it if
- You need a MERV rating above 11
- You want fewer than 6 filters in a pack
The filters measure 12 x 20 x 1 inches, with an actual size of 11.75 x 19.75 x 0.75 inches, and carry a MERV 11 rating in a 6-pack. The pleated design offers a higher pleat count than most retail, with filtration lasting up to 3 months. Replacement follows airflow arrows into the filter slot for central units or return grilles, and the filters are made in the USA using 100% American components, including recycled materials.
Flanders/Precisionaire 12x20x1 Fiberglass Furnace Filters
A pack of 12 fiberglass 12x20x1 filters, the most filters in a pack here.
- Pack size: 12-pack, the most here
Good for
- Buyers who want 12 fiberglass filters in one pack
- Owners of 12x20x1 slots who stock up
Skip it if
- You want fewer than 12 filters in one pack
- You need a size other than 12x20x1
This is a pack of 12 fiberglass furnace filters in size 12x20x1. Fiberglass is the filter medium for this pack, and the size matches the 12x20x1 search. The pack size is 12.
How to choose
Match the size to your slot
A 12x20x1 filter is a nominal size, and the actual size varies by brand. The Filter King measures 11.5 x 19.5 x .75 inches actual, the Filtrete measures 11.81 x 19.81 x 0.78 inches actual, and the Simply measures 11.75 x 19.75 x 0.75 inches actual. Measure the slot before ordering, and compare the actual size against the slot rather than the nominal size alone.
Compare MERV ratings and pack sizes
A MERV rating grades how well a filter captures particles, with a higher number meaning a finer rating. This list includes MERV 8 for the Filter King, MERV 11 for the Simply and MERV 13 with MPR 1900 for the Filtrete. Pack size matters just as much for stocking up: the Filter King and Simply come in 6-packs, the Filtrete in a 2-pack, and the Flanders in a pack of 12.
Plan the change interval
Change intervals differ across this list. The Filter King filters last up to 90 days, with a recommended change every 30 to 90 days for 1 inch filters. The Filtrete filters carry a change recommendation of at least once every 90 days, with app reminders at 30, 60 or 90 days. The Simply filters last up to 3 months, and replacement follows the airflow arrows into the filter slot.
FAQ
What does MERV mean on a furnace filter?
MERV is the rating that grades a filter, and this list includes MERV 8, MERV 11 and MERV 13 filters in 12x20x1.
When should I change a 12x20x1 filter?
Change 1 inch filters every 30 to 90 days for the Filter King, at least once every 90 days for the Filtrete, and up to 3 months for the Simply filters.
What is the actual size of a 12x20x1 filter?
Actual sizes differ by brand: Filter King 11.5 x 19.5 x .75 inches, Filtrete 11.81 x 19.81 x 0.78 inches, and Simply 11.75 x 19.75 x 0.75 inches.
Do these filters come in multi-packs?
Yes. The Filter King and Simply filters come in 6-packs, the Filtrete filters come in a 2-pack, and the Flanders filters come in a pack of 12.
