Furnace Filters
Best 16x21x1 Furnace Filter (2026): Our 5 Picks Ranked
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 the search best 16x21x1 furnace filter, the Amazon Basics 16x20x1 Air Filter 6-Pack leads this list: it pairs a MERV 8 rating with electrostatic pleated media and a 6-pack supply. The Filter King 16x21x1 Air Filter is the nominal size match at a MERV 8 rating, while the Aerostar MERV 11 pick traps finer particles.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
-
Best OverallAmazon Basics 16x20x1 Air Filter 6-Pack9.8 View on Amazon -
Runner-UpFilter King 16x21x1 Air Filter9.7 View on Amazon -
9.7 View on Amazon -
Also GreatFiltrete 16x21x1 Air Filter9.5 View on Amazon -
9.2 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. Amazon Basics 16x20x1 Air Filter 6-Pack | MERV 8 | 6-pack | — | — |
| 2. Filter King 16x21x1 Air Filter | MERV 8 | 4-pack | — | — |
| 3. Aerostar 16.375x21.5x1 MERV 11 Air Filter | MERV 11 | 4-pack | — | — |
| 4. Filtrete 16x21x1 Air Filter | MERV 8 | 2-pack | — | — |
| 5. WATTRIP 2-Pack 16x21x1 MERV 8 Reusable HVAC Electrostatic | MERV 8 | 2-pack | — | 1-year |
Amazon Basics 16x20x1 Air Filter 6-Pack
It pairs a MERV 8 rating with electrostatic pleated media, a beverage board frame and a 6-pack supply.
- MERV rating: MERV 8
- Pack size: 6-pack, the most here
Good for
- Buyers who want six replacement filters on hand
- Owners of furnaces that take a nominal 16x20x1 filter
Skip it if
- You need a nominal 16x21x1 size
- You want a filter rated above MERV 8
It has a nominal size of 16x20x1 with an actual size of 15.75 by 19.75 by 0.75 inches, and it fits standard furnaces, ACs and HVAC return grilles. The synthetic media is electrostatically charged to attract particles as small as 3 microns, with a beverage board frame and wire mesh support. The airflow arrow points toward the furnace, and the 6-pack covers up to 12 months with changes every 60 to 90 days.
Filter King 16x21x1 Air Filter
It is the nominal 16x21x1 size at a MERV 8 rating, with a pleated electrostatic design and a 4-pack supply.
- MERV rating: MERV 8
- Pack size: 4-pack
Good for
- Buyers who want a nominal 16x21x1 filter
- Owners who want a filter made in the USA
Skip it if
- You want a rating above MERV 8
- You want more than 4 filters in a pack
It has a nominal size of 16 by 21 by 1 inches with an actual size of 16 by 21 by 0.75 inches, and it is made in the USA. The pleated design captures particles without restricting airflow, and the filter lasts up to 90 days before replacement. The maker recommends changing a 1 inch filter every 30 to 90 days.
Aerostar 16.375x21.5x1 MERV 11 Air Filter
It steps up to a MERV 11 rating with MPR 1200 and FPR 7 comparability, in a 4-pack for standard 1-inch slots.
- MERV rating: MERV 11
- Pack size: 4-pack
Good for
- Buyers who want a MERV 11 rating
- Owners of residential or commercial HVAC systems
Skip it if
- You need a nominal 16x21x1 size
- You want a rating below MERV 11
It has an actual size of 16.50 by 21.50 by 0.75 inches, with a sturdy beverage board frame and wire backing. It is made in the USA, and the maker states replacement every 2 to 3 months.
Filtrete 16x21x1 Air Filter
It pairs a MERV 8 rating with MPR 700, a 3-month design and a 2-pack with an app replacement countdown.
- MERV rating: MERV 8
- Pack size: 2-pack
Good for
- Buyers who want a 3-month filter with an app reminder
- Owners who want MPR 700 rated filtration
Skip it if
- You want more than 2 filters in a pack
- You want a rating above MERV 8
It has an actual size of 15.69 by 20.69 by 0.81 inches, with a 3-month pleated design for furnaces and air conditioners. The Filtrete Smart App scans the barcode and counts down 30, 60 or 90 days to the next change.
WATTRIP 2-Pack 16x21x1 MERV 8 Reusable HVAC Electrostatic
It is a washable reusable MERV 8 filter with a metal frame, 7-layer filtration and a 1-year warranty.
- MERV rating: MERV 8
- Pack size: 2-pack
- 1-year warranty stated
Good for
- Buyers who want a washable filter they reuse
- Owners who want a metal frame that resists deformation
Skip it if
- You want a rating above MERV 8
- You want more than 2 filters in a pack
It has an actual size of 15-5/8 by 20-5/8 by 7/8 inches, with a reinforced aluminum frame and an upgraded painted steel mesh. The 7-layer design has 4 layers of metal mesh, 2 layers of nylon media and 1 filter cotton layer, capturing dust, lint and pet hair. Rinse or vacuum it to clean, wash every 1 to 3 months, and let it dry fully before reinstalling. It carries a 1-year warranty.
How to choose
Best 16x21x1 furnace filter sizing
Nominal size and actual size are not the same number. The Filter King is nominal 16 by 21 by 1 inches with an actual size of 16 by 21 by 0.75 inches, while the Amazon Basics pick is nominal 16x20x1 with an actual size of 15.75 by 19.75 by 0.75 inches. Check the size printed on your current filter frame before you order, and match the nominal size the maker gives.
MERV rating and what it means
A MERV rating grades how fine a particle a filter captures, with a higher number catching smaller particles. The Aerostar is rated MERV 11 with MPR 1200 and FPR 7 comparability, while the other four picks are rated MERV 8. A higher rating is not always the right call for every system, so compare the rating with the size and the change interval your system needs.
Change intervals and pack sizes
Pack size decides how many spares you keep on hand, and the change interval decides when you swap. The Amazon Basics 6-pack covers up to 12 months with changes every 60 to 90 days, while the Filter King 4-pack lasts up to 90 days per filter. The Filtrete 2-pack uses a 3-month design with an app countdown, and the WATTRIP 2-pack washes clean every 1 to 3 months instead of being replaced.
FAQ
What size filter do I need for my furnace?
Check the nominal size on your current filter frame. The Filter King pick is nominal 16 by 21 by 1 inches, while the Amazon Basics pick is nominal 16x20x1, so the two are not the same size.
When should I change a furnace filter?
It depends on the pick. The Amazon Basics 6-pack changes every 60 to 90 days, the Filter King lasts up to 90 days, and the Filtrete changes at least every 90 days for 1 inch filters.
What does a MERV 8 rating mean?
MERV grades how fine a particle a filter captures, and MERV 8 is the rating on four of these picks. The Aerostar is the exception at MERV 11, with MPR 1200 and FPR 7 comparability.
Can I wash and reuse a furnace filter?
Only the WATTRIP pick is washable and reusable: rinse or vacuum it, wash every 1 to 3 months, and let it dry fully before reinstalling. The other picks are pleated filters changed on a schedule.
