Furnace Filters
Best 20x25 Furnace Filter (2026): Our 5 Picks Ranked
As an Amazon Associate I earn from qualifying purchases. Specs below come from each product's Amazon listing; we do not test products in person.
For the search for the best 20x25 furnace filter, the Simply 20x25x1 leads as Best Overall with MERV 8 filtration in a 6-pack and up to 3 months of filtration. The rest of the list covers MERV 5, MERV 8 and MERV 13 options, plus a 12-pack for buyers who want more filters in one box.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallSimply 20x25x1 Air Filter9.8 View on Amazon -
Runner-UpFiltrete 20x25x1 Air Filter9.8 View on Amazon -
Also GreatAmazon Basics MERV 5 AC Furnace Air9.5 View on Amazon -
Most in the PackFilter King 20x25x2 Air Filter MERV9.5 View on Amazon -
Also GreatAerostar Air Filter 20x25x1 MERV 13 AC9.2 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. Simply 20x25x1 Air Filter | MERV 8 | 6-pack | — | — |
| 2. Filtrete 20x25x1 Air Filter | MERV 5 | 6-pack | — | — |
| 3. Amazon Basics MERV 5 AC Furnace Air | MERV 5 | 6-pack | — | — |
| 4. Filter King 20x25x2 Air Filter MERV | MERV 8 | 12-pack | — | — |
| 5. Aerostar Air Filter 20x25x1 MERV 13 AC | MERV 13 | 6-pack | — | — |
Simply 20x25x1 Air Filter
It pairs MERV 8 filtration with a 6-pack and up to 3 months of filtration in the standard 20x25x1 size.
- MERV rating: MERV 8
- Pack size: 6-pack
Good for
- Buyers who want MERV 8 filtration in a 6-pack
- Owners replacing a 20x25x1 filter in a furnace or AC unit
Skip it if
- You need more than 6 filters in one box
- You need a filter thicker than 0.75 inches
Follow the airflow arrows and insert it into the filter slot for central units or return grilles. It is made in the USA from 100% American components, including recycled materials.
Filtrete 20x25x1 Air Filter
It offers MERV 5 filtration with 300 MPR in a 6-pack, plus app reminders for filter changes.
- MERV rating: MERV 5
- Pack size: 6-pack
Good for
- Buyers who want MERV 5 filtration for a standard HVAC system
- Buyers who want phone reminders to change the filter
Skip it if
- You need filtration above MERV 5
- You need more than 6 filters in one box
It has an actual size of 19.69 by 24.69 by 0.81 inches, slightly smaller than the nominal 20x25x1 size. Its 3-in-1 technology pulls in and traps particles from the air passing through it. Change it at least once every 90 days, and the Filtrete Smart App sets 30-, 60- or 90-day reminders.
Amazon Basics MERV 5 AC Furnace Air
It gives MERV 5 filtration in a 6-pack with a beverage board frame and wire mesh support.
- MERV rating: MERV 5
- Pack size: 6-pack
Good for
- Buyers who want a MERV 5 filter for standard furnaces or AC units
- Buyers who want a 6-pack for return grilles
Skip it if
- You need filtration above MERV 5
- You need more than 6 filters in one box
It has an actual size of 19.75 by 24.75 by 0.75 inches. Insert it with the airflow arrow pointing toward the furnace or blower, away from the return grille. Replace it every 60 to 90 days for optimal performance.
Filter King 20x25x2 Air Filter MERV
It has a 12-pack of MERV 8 filters in the 20x25x2 size.
- MERV rating: MERV 8
- Pack size: 12-pack, the most here
Good for
- Buyers who want 12 MERV 8 filters in one box
- Owners with a 2-inch filter slot
Skip it if
- You need a filter thinner than 1.75 inches
- You need filtration above MERV 8
It has an actual size of 19.5 by 24.5 by 1.75 inches. The pleated design captures more particles and extends the life of the filter. It can last up to 90 days before needing replacement, and installation is open, slide and close.
Aerostar Air Filter 20x25x1 MERV 13 AC
It brings MERV 13 filtration to the 20x25x1 size in a 6-pack, with electrostatically charged pleated fibers.
- MERV rating: MERV 13
- Pack size: 6-pack
Good for
- Buyers who want MERV 13 filtration for a 1-inch slot
- Buyers who want a 6-pack with up to 3 months of filtration
Skip it if
- You need a filter thicker than 0.75 inches
- You need filtration below MERV 13
It has an actual size of 19.75 by 24.75 by 0.75 inches. The heavy-duty beverage board frame has moisture-resistant backing and reinforced pleats, and it provides up to 3 months of filtration.
How to choose
Nominal size versus actual size
A filter sold as 20x25x1 carries a nominal size, and the actual filter measures slightly smaller. The Simply and Amazon Basics filters measure 19.75 by 24.75 by 0.75 inches, the Filtrete measures 19.69 by 24.69 by 0.81 inches, and the Filter King measures 19.5 by 24.5 by 1.75 inches. Check the actual size against the slot before ordering, and select the nominal size based on the current filter's frame or measurements.
What MERV ratings mean
MERV rates how a filter captures particles, and higher MERV ratings capture smaller airborne particles, while lower MERV ratings allow for increased airflow. This list includes MERV 5 filters from Filtrete and Amazon Basics, MERV 8 filters from Simply and Filter King, and a MERV 13 filter from Aerostar. Match the rating to the particles you want captured and the airflow your system needs.
Replacement timing and airflow direction
Change intervals differ across this list, so follow the figure for the filter you buy. Simply and Aerostar provide up to 3 months of filtration, Filtrete asks for a change at least once every 90 days, Amazon Basics asks for replacement every 60 to 90 days, and Filter King can last up to 90 days. Point the airflow arrow toward the furnace or blower, away from the return grille.
FAQ
What does MERV mean on a furnace filter?
MERV is the rating for how a filter captures particles. Higher MERV ratings capture smaller airborne particles, while lower MERV ratings allow for increased airflow. This list includes MERV 5, MERV 8 and MERV 13 filters.
Will a 20x25x1 filter fit my furnace?
Check the actual size, not only the nominal size. The Simply and Amazon Basics filters measure 19.75 by 24.75 by 0.75 inches, and the Filtrete measures 19.69 by 24.69 by 0.81 inches. Select the nominal size based on your current filter's frame or measurements.
When should I change a 20x25 furnace filter?
Follow the interval for the filter you buy. Simply and Aerostar provide up to 3 months of filtration, Filtrete asks for a change at least once every 90 days, Amazon Basics asks for replacement every 60 to 90 days, and Filter King can last up to 90 days.
What is the difference between the MERV 8 and MERV 13 picks?
Simply and Filter King are MERV 8, while Aerostar is MERV 13. Higher MERV ratings capture smaller airborne particles, and Aerostar captures up to 98% of airborne particles.
