Furnace Filters
Best 20x24 Furnace Filters (2026): 5 Models Side by Side
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For 20x24 furnace filters, the Simply MERV 8 6-pack leads with a pleated MERV 8 filter in the search size. The Filtrete MERV 13 2-pack offers a MERV 13 rating with a 1900 MPR rating, and the Glasfloss MERV 10 box of 6 offers a MERV 10 rating with a heavy-duty frame. All five match the 20 by 24 by 1 inch nominal size, so choose by MERV rating and pack size.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallSimply 20x24x1 Air Filter9.8 View on Amazon -
Runner-UpFilter King 20x24x1 Air Filter MERV9.7 View on Amazon -
Also GreatFiltrete 20x24x1 Air Filter9.5 View on Amazon -
9.3 View on Amazon -
Also GreatFlanders Ez Flow Ii MERV 4 Economy9.2 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 20x24x1 Air Filter | MERV 8 | 6-pack | — | — |
| 2. Filter King 20x24x1 Air Filter MERV | MERV 8 | 6-pack | — | — |
| 3. Filtrete 20x24x1 Air Filter | MERV 13 | 2-pack | — | — |
| 4. Glasfloss 20x24x1 MERV 10 Pleated AC Furnace | MERV 10 | — | — | — |
| 5. Flanders Ez Flow Ii MERV 4 Economy | MERV 4 | — | — | — |
Simply 20x24x1 Air Filter
A pleated MERV 8 filter in a 6-pack with a 19.75 by 23.75 by 0.75 inch actual size for the search size.
- 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 filter made in USA
Skip it if
- You need more than 6 filters at once
- You want a MERV rating above 8
It measures 20 by 24 by 1 inches nominal, with an actual size of 19.75 by 23.75 by 0.75 inches, and the pleated design suits central units or return grilles. It lasts up to 3 months before replacement, and airflow arrows guide insertion into the filter slot. The 6-pack covers repeated changes, and the filters use recycled materials.
Filter King 20x24x1 Air Filter MERV
A pleated MERV 8 filter in a 6-pack for the search size.
- 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 filter with fast installation
Skip it if
- You need more than 6 filters at once
- You want a MERV rating above 8
It lasts up to 90 days before replacement, with a recommended change every 30 to 90 days for 1 inch filters. Installation is open, slide and close.
Filtrete 20x24x1 Air Filter
A MERV 13 filter with a 1900 MPR rating in a 2-pack for the search size.
- MERV rating: MERV 13
- Pack size: 2-pack
Good for
- Buyers who want a MERV 13 filter
- Buyers who want app reminders for filter changes
Skip it if
- You need more than 2 filters at once
- You want a MERV rating below 13
It carries a MERV 13 rating with a 1900 MPR rating and a 62% microparticle capture rate for particles between 0.3 and 1 micron. The 2-pack covers 3-month changes, with a recommended change at least once every 90 days. The Filtrete Smart App sets 30-, 60- or 90-day reminders to change the filter, and the filters use 3-in-1 technology to pull in and trap particles.
Glasfloss 20x24x1 MERV 10 Pleated AC Furnace
A MERV 10 pleated filter in a box of 6 with a heavy-duty frame for the search size.
- MERV rating: MERV 10
Good for
- Buyers who want a MERV 10 filter
- Buyers who want a heavy-duty frame that resists buckling
Skip it if
- You need more than 6 filters at once
- You want a MERV rating above 10
It carries a MERV 10 rating with an MPR 800 rating and an FPR 7 rating, and the exact size is 19-3/8 by 23-3/8 by 7/8 inches. The heavy-duty frame resists buckling, and the MERV 10 filtration offers similar air flow and resistance as a MERV 8 filter. It is made in the USA, and the recommended change is at least every 3 months.
Flanders Ez Flow Ii MERV 4 Economy
A MERV 4 economy fiberglass filter sold as 12 per case for the search size.
- MERV rating: MERV 4
Good for
- Buyers who want a 12-count case of filters
- Buyers who want an economy fiberglass filter
Skip it if
- You want a MERV rating above 4
- You want fewer than 12 filters at once
It is a MERV 4 economy fiberglass filter in the 20 by 24 by 1 inch size, sold as 12 per case. The case quantity covers many changes from one purchase.
How to choose
Match the nominal size to your slot
All five filters carry the 20 by 24 by 1 inch nominal size, but actual sizes differ: the Simply measures 19.75 by 23.75 by 0.75 inches, the Filter King measures 19.5 by 23.5 by 0.75 inches, the Filtrete measures 19.81 by 23.81 by 0.78 inches, and the Glasfloss measures 19-3/8 by 23-3/8 by 7/8 inches. Check the slot in your furnace or return grille against the actual size before ordering, since a filter that is too large will not fit and one that is too small leaves gaps.
Compare MERV ratings and pack sizes
MERV ratings in this group run from MERV 4 to MERV 13: the Flanders carries MERV 4, the Simply and Filter King carry MERV 8, the Glasfloss carries MERV 10, and the Filtrete carries MERV 13 with a 1900 MPR rating. Pack sizes differ too: the Filtrete comes as a 2-pack, the Simply, Filter King and Glasfloss come as 6-packs, and the Flanders comes as 12 per case. A higher MERV rating captures smaller particles, so match the rating to what your system handles and the pack size to your change schedule.
Set a replacement schedule
The Filter King recommends a change every 30 to 90 days, the Simply lasts up to 3 months, the Filtrete recommends a change at least once every 90 days, and the Glasfloss recommends a change at least every 3 months. The Filtrete Smart App sets 30-, 60- or 90-day reminders, which helps if you want a prompt. Write the install date on the frame edge when you fit a new filter so the next change is easy to track.
FAQ
What is the actual size of a 20x24x1 filter?
Nominal size is 20 by 24 by 1 inches, but actual sizes differ by brand. The Simply measures 19.75 by 23.75 by 0.75 inches, the Filter King measures 19.5 by 23.5 by 0.75 inches, and the Filtrete measures 19.81 by 23.81 by 0.78 inches.
What MERV ratings do these filters carry?
The Flanders carries MERV 4, the Simply and Filter King carry MERV 8, the Glasfloss carries MERV 10, and the Filtrete carries MERV 13 with a 1900 MPR rating.
When should these filters be changed?
The Filter King recommends every 30 to 90 days, the Simply lasts up to 3 months, and the Filtrete and Glasfloss recommend a change at least every 90 days or 3 months. The Filtrete Smart App can set 30-, 60- or 90-day reminders.
Do these filters come in multi-packs?
Yes. The Simply, Filter King and Glasfloss come as 6-packs, the Filtrete comes as a 2-pack, and the Flanders comes as 12 per case.
