Furnace Filters
Best 12x20x1 Furnace Filter (2026): Top 5 by the Specs
As an Amazon Associate we earn from qualifying purchases. Specs below come from each product's Amazon listing; we do not test products in person.
For a 12x20x1 furnace filter, the Filtrete leads this list: it pairs MERV 5 with MPR 300 in a 6-pack of 3-month pleated filters. If you want a higher MERV, the K&N offers MERV 11 in a washable filter with a lifetime warranty.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallFiltrete 12x20x1 Air Filter9.8 View on Amazon -
9.6 View on Amazon -
Also GreatSimply 12x20x1 Air Filter9.5 View on Amazon -
Also GreatFilter King 12x20x1 Air Filter MERV9.5 View on Amazon -
Also GreatK&N 12x20x1 HVAC Furnace Air Filter9.2 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 12x20x1 Air Filter | MERV 5 | 6-pack | — | — |
| 2. Generic Proairtek AF12201M08SWH Model 12x20x1 Air Filter | MERV 8 | — | — | — |
| 3. Simply 12x20x1 Air Filter | MERV 8 | 12-pack | — | — |
| 4. Filter King 12x20x1 Air Filter MERV | MERV 8 | 6-pack | — | — |
| 5. K&N 12x20x1 HVAC Furnace Air Filter | MERV 11 | — | — | lifetime |
Filtrete 12x20x1 Air Filter
It pairs MERV 5 with MPR 300 in a 6-pack of pleated 3-month filters for standard HVAC systems.
- MERV rating: MERV 5
- Pack size: 6-pack
Good for
- Buyers who want a 6-pack of 3-month filters
- Buyers who want app reminders to change filters
Skip it if
- You want a MERV above 5
- You want a pack with more than 6 filters
It uses pleated polypropylene construction with 3-in-1 technology to trap particles. Its actual size is 11.81 inches by 19.81 inches by 0.81 inches, and it slides into furnace and air conditioner units. It captures dust, lint and dust mite debris, and it changes at least once every 90 days.
Generic Proairtek AF12201M08SWH Model 12x20x1 Air Filter
It pairs MERV 8 with a paper build in a rectangular slide-in filter.
- MERV rating: MERV 8
Good for
- Buyers who want a MERV 8 filter for a furnace
- Buyers who want a paper filter that slides in
Skip it if
- You want a MERV above 8
- You want a filter thicker than 1 inch
It is a MERV 8 rectangular filter that slides into an air handler or furnace. It measures 20 inches by 12 inches by 1 inch and is made of paper. It offers enhanced airflow and efficiency.
Simply 12x20x1 Air Filter
It pairs MERV 8 with MPR 600 in a 12-pack of pleated filters that last up to 3 months.
- MERV rating: MERV 8
- Pack size: 12-pack
Good for
- Buyers who want a 12-pack of MERV 8 filters
- Buyers who want MPR 600 pleated filters
Skip it if
- You want a MERV above 8
- You want a pack with more than 12 filters
Its actual size is 11.75 inches by 19.75 inches by 0.75 inches, and it filters particles from 3.0 to 10.0 microns. It lasts up to 3 months.
Filter King 12x20x1 Air Filter MERV
It pairs MERV 8 with a 6-pack of pleated filters that last up to 90 days.
- MERV rating: MERV 8
- Pack size: 6-pack
Good for
- Buyers who want a 6-pack of MERV 8 filters
- Buyers who want a pleated polypropylene filter
Skip it if
- You want a MERV above 8
- You want a pack with more than 6 filters
It is a pleated polypropylene filter with an actual size of 11.5 inches by 19.5 inches by 0.75 inches. It captures particles without impacting airflow, and it changes every 30 to 90 days for 1-inch filters. It slides into air conditioner and furnace units.
K&N 12x20x1 HVAC Furnace Air Filter
It pairs MERV 11 with a washable, reusable filter that carries a lifetime warranty.
- MERV rating: MERV 11
- Lifetime warranty stated
Good for
- Buyers who want a reusable washable filter
- Buyers who want a MERV 11 filter
Skip it if
- You want a MERV above 11
- You want a filter thicker than 0.8 inches
It is a pleated synthetic polymer filter with MERV 11. It is washable and reusable, and it cleans by rinsing with a low-pressure hose after the cleaner is applied. It measures 19.6 inches by 11.6 inches by 0.8 inches and carries a lifetime warranty.
How to choose
MERV and MPR scales
MERV and MPR are two scales that describe what a filter captures. The Filtrete is MERV 5 with MPR 300, the Proairtek, Simply and Filter King are MERV 8, and the K&N is MERV 11. The Simply adds MPR 600. A higher number on either scale means finer capture, so match the number to the particles you want caught.
Nominal size versus actual size
A 12x20x1 filter is a nominal size, and the actual size runs slightly smaller. The Filtrete measures 11.81 by 19.81 by 0.81 inches, the Simply measures 11.75 by 19.75 by 0.75 inches, and the Filter King measures 11.5 by 19.5 by 0.75 inches. Check the actual size against your filter slot before you buy.
Pack size and replacement timing
Pack size sets how many changes one buy covers. The Filtrete and Filter King come in 6-packs, the Simply comes in a 12-pack, and the K&N is washable and reusable. The Filtrete changes at least once every 90 days, the Filter King every 30 to 90 days, and the Simply lasts up to 3 months.
FAQ
What MERV values do these filters have?
The Filtrete is MERV 5, the Proairtek, Simply and Filter King are MERV 8, and the K&N is MERV 11.
When should I change these filters?
The Filtrete changes at least once every 90 days, the Filter King every 30 to 90 days, and the Simply lasts up to 3 months. The K&N is washable and reusable instead of disposable.
What size are these filters actually?
The Filtrete measures 11.81 by 19.81 by 0.81 inches, the Simply measures 11.75 by 19.75 by 0.75 inches, and the Filter King measures 11.5 by 19.5 by 0.75 inches.
