Furnace Filters
Best 18x30 AC Filter (2026): Our 4 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 an 18x30 slot, the Simply leads this list: a Merv 8 rating in a 6-pack with pleated filters. The Runner-Up Filter King matches the MERV 8 rating in a 6-pack, while the Filtrete gives a MERV 12 rating in a 6-pack and the Aerostar gives a MERV 8 rating in a 4-pack.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallSimply 18x30x1 Air Filter9.8 View on Amazon -
Runner-UpFilter King 18x30x1 Air Filter MERV9.6 View on Amazon -
Also GreatFiltrete 18x30x1 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. Simply 18x30x1 Air Filter | MERV 8 | 6-pack | — | — |
| 2. Filter King 18x30x1 Air Filter MERV | MERV 8 | 6-pack | — | — |
| 3. Filtrete 18x30x1 Air Filter | MERV 12 | 6-pack | — | — |
| 4. Aerostar 18x30x1 MERV 8 Pleated Air Filter | MERV 8 | 4-pack | — | — |
Simply 18x30x1 Air Filter
It earns Best Overall with a Merv 8 rating, a 6-pack and pleated filters that trap 90% of airborne particles.
- MERV rating: MERV 8
- Pack size: 6-pack
Good for
- Buyers who want a Merv 8 filter in a 6-pack
- Buyers who want filters that trap 90% of airborne particles
Skip it if
- You want a MERV rating above 8
- You want a pack of fewer than 6 filters
It has a Merv 8 rating and a 6-pack with an actual size of 17.75x29.75x0.75 inches. The pleated filters trap 90% of airborne particles and give up to 3 months of filtration. The filters use American components and follow airflow arrows for insertion.
Filter King 18x30x1 Air Filter MERV
It earns Runner-Up with a MERV 8 rating, a 6-pack and a pleated design that captures more particles.
- MERV rating: MERV 8
- Pack size: 6-pack
Good for
- Buyers who want a MERV 8 filter in a 6-pack
- Buyers who want a filter that lasts up to 90 days
Skip it if
- You want a MERV rating above 8
- You want a filter thinner than 0.75 inches
It has a MERV 8 rating and a 6-pack with an actual size of 17.5 x 29.5 x .75. The pleated design captures more particles without impacting air flow, and filters last up to 90 days before needing replacement. Change intervals run every 30 to 90 days for 1 inch filters.
Filtrete 18x30x1 Air Filter
It pairs a MERV 12 rating with a 6-pack and 3-in-1 technology for trapping particles.
- MERV rating: MERV 12
- Pack size: 6-pack
Good for
- Buyers who want a MERV 12 filter in a 6-pack
- Buyers who want app reminders for filter changes
Skip it if
- You want a MERV rating below 12
- You want a pack of fewer than 6 filters
It has a MERV 12 rating with a 1500 MPR and a 6-pack of 3-month pleated filters. The actual size is 17.81x29.81x0.78 in, and change intervals run at least once every 90 days. The Filtrete Smart App sets 30-, 60- or 90-day reminders.
Aerostar 18x30x1 MERV 8 Pleated Air Filter
It pairs a MERV 8 rating with a 4-pack and electrostatic media for high efficiency.
- MERV rating: MERV 8
- Pack size: 4-pack
Good for
- Buyers who want a MERV 8 filter in a 4-pack
- Buyers who want electrostatic media with low air flow resistance
Skip it if
- You want a MERV rating above 8
- You want a pack of 6 filters
It has a MERV 8 rating and a 4-pack with electrostatic media for high efficiency and low air flow resistance. Change intervals run every 60 to 90 days, and every 30 days during peak summer and winter months.
How to choose
Match MERV rating to the job
MERV ratings set how fine the trapped particles are. The Filtrete carries a MERV 12 rating, while the Simply, Filter King and Aerostar filters carry a MERV 8 rating. A higher MERV rating traps finer particles, so match the rating to the dust and particles in the home. Check the rating on the pack before buying.
Check the actual size first
Nominal size and actual size differ on every filter here. The Simply measures 17.75x29.75x0.75 inches, the Filter King measures 17.5 x 29.5 x .75 and the Filtrete measures 17.81x29.81x0.78 in. Measure the slot before ordering, since a filter that does not fit the slot will not sit right.
Plan the change interval
The Filtrete runs at least once every 90 days, the Filter King runs every 30 to 90 days for 1 inch filters, and the Aerostar runs every 60 to 90 days, or every 30 days during peak summer and winter months. The Simply gives up to 3 months of filtration. Buy the pack size that covers the next few changes.
FAQ
What MERV rating do these 18x30 filters carry?
The Filtrete carries a MERV 12 rating, while the Simply, Filter King and Aerostar carry a MERV 8 rating.
How many filters come in each pack?
The Simply, Filter King and Filtrete come in 6-packs, and the Aerostar comes in a 4-pack.
What change intervals do these filters give?
The Filtrete runs at least once every 90 days, the Filter King runs every 30 to 90 days for 1 inch filters, and the Aerostar runs every 60 to 90 days.
Do these filters fit a standard 18x30 slot?
Nominal size is 18x30x1 on all four, but actual sizes differ: the Simply is 17.75x29.75x0.75 inches and the Filtrete is 17.81x29.81x0.78 in, so measure the slot first.
