Furnace Filters
Best 18x25x1 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 an 18x25x1 furnace filter, the True Blue leads this list: it pairs a MERV 11 rating with a 4-pack and electrostatic charged media that traps up to 79% of particles sized 3.0-10.0 microns. The Simply and the Filtrete both carry a MERV 8 rating, while the Chenzhit carries a MERV 13 rating with a 6-pack.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallTrue Blue Allergen 18x25x1 Air Filter9.8 View on Amazon -
Runner-UpSimply 18x25x1 Air Filter9.8 View on Amazon -
Also GreatFiltrete 18x25x1 Air Filter9.5 View on Amazon -
Also GreatAIRx Filters 18x25x1 Furnace & AC Filter9.4 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. True Blue Allergen 18x25x1 Air Filter | MERV 11 | 4-pack | — | — |
| 2. Simply 18x25x1 Air Filter | MERV 8 | 4-pack | — | — |
| 3. Filtrete 18x25x1 Air Filter | MERV 8 | — | — | — |
| 4. AIRx Filters 18x25x1 Furnace & AC Filter | MERV 8 | — | — | — |
| 5. Chenzhit (6-Pack) 18x25x1 Furnace Air Filters | MERV 13 | — | — | — |
True Blue Allergen 18x25x1 Air Filter
It pairs a MERV 11 rating with electrostatic charged media and a 4-pack for 18x25x1 furnace and HVAC use.
- MERV rating: MERV 11
- Pack size: 4-pack
Good for
- Buyers who want a MERV 11 filter in a 4-pack
- Buyers who want electrostatic charged media
Skip it if
- You need a MERV rating above 11
- You want a pack larger than 4 filters
The electrostatic charged media uses static electricity to attract and trap smaller airborne particles. Change it at least every 4 months, and it fits air conditioners, furnaces, heat pumps and HVAC units.
Simply 18x25x1 Air Filter
It pairs a MERV 8 rating with a 4-pack and pleated media that traps 90% of airborne particles.
- MERV rating: MERV 8
- Pack size: 4-pack
Good for
- Buyers who want a MERV 8 filter in a 4-pack
- Buyers who want pleated media that traps 90% of airborne particles
Skip it if
- You need a MERV rating above 8
- You want a pack larger than 4 filters
It measures 18 inches by 25 inches by 1 inch, with an actual size of 17.75 inches by 24.75 inches by 0.75 inches. It lasts up to 3 months and fits air conditioners, furnaces and heat pumps.
Filtrete 18x25x1 Air Filter
It pairs a MERV 8 rating with MPR 700 and 3-in-1 technology.
- MERV rating: MERV 8
Good for
- Buyers who want MPR 700 with a MERV 8 rating
- Buyers who want a 3-month pleated filter
Skip it if
- You need a MERV rating above 8
- You want a change interval longer than 3 months
It carries both MERV and MPR ratings, with MPR 700 rated at MERV 8. Change it at least every 90 days, and the Smart App sets 30, 60 or 90 day replacement countdowns.
AIRx Filters 18x25x1 Furnace & AC Filter
It pairs a MERV 8 rating with a 6-pack and electrostatic pleated media for up to 90 days of use.
- MERV rating: MERV 8
Good for
- Buyers who want a MERV 8 filter in a 6-pack
- Buyers who want electrostatic pleated media
Skip it if
- You need a MERV rating above 8
- You want a pack larger than 6 filters
It captures airborne particles with a MERV 8 rating and electrostatic pleated media. Its design minimizes resistance to airflow, and it lasts up to 90 days. It fits air conditioners and furnaces.
Chenzhit (6-Pack) 18x25x1 Furnace Air Filters
It pairs a MERV 13 rating with MPR 1900 and FPR 10 in a 6-pack for 18x25x1 furnace and HVAC use.
- MERV rating: MERV 13
Good for
- Buyers who want a MERV 13 filter in a 6-pack
- Buyers who want MPR 1900 and FPR 10 ratings
Skip it if
- You need a MERV rating above 13
- You want a pack larger than 6 filters
It measures 18 inches by 25 inches by 1 inch, with an actual size of 17.75 inches by 24.75 inches by 0.75 inches. Its MERV 13 rating equals MPR 1900 and FPR 10, with 98% airborne particle filtration. Replace it every 60 to 90 days, or every 30 days during peak summer and winter.
How to choose
MERV ratings and particle capture
A MERV rating grades how well a filter traps particles. The True Blue carries MERV 11, the Simply and the Filtrete carry MERV 8, the AIRx carries MERV 8, and the Chenzhit carries MERV 13. Higher numbers trap smaller particles: the True Blue traps up to 79% of particles sized 3.0-10.0 microns, and the Chenzhit filters 98% of airborne particles.
Check the 18x25x1 fit
Nominal size and actual size differ on these filters. The Simply measures 17.75 inches by 24.75 inches by 0.75 inches, the Filtrete measures 17.81 inches by 24.81 inches by 0.81 inches, and the AIRx measures 17.5 inches by 24.5 inches by 0.75 inches. Measure your current filter for the exact size and compare it to the size of the pick before you buy.
Replacement intervals and packs
The True Blue changes at least every 4 months, the Simply lasts up to 3 months, the Filtrete changes at least every 90 days, and the AIRx lasts up to 90 days. The Chenzhit changes every 60 to 90 days, or every 30 days during peak summer and winter. Pack counts differ too: the True Blue and the Simply come in 4-packs, while the AIRx and the Chenzhit come in 6-packs.
FAQ
What MERV ratings do these filters carry?
The True Blue carries MERV 11, the Simply, the Filtrete and the AIRx carry MERV 8, and the Chenzhit carries MERV 13.
When should I change each filter?
The True Blue changes at least every 4 months and the Simply lasts up to 3 months. The Filtrete changes at least every 90 days and the AIRx lasts up to 90 days. The Chenzhit changes every 60 to 90 days.
What sizes do these filters actually measure?
The Simply measures 17.75 inches by 24.75 inches by 0.75 inches, the Filtrete measures 17.81 inches by 24.81 inches by 0.81 inches, and the AIRx measures 17.5 inches by 24.5 inches by 0.75 inches. The Chenzhit measures 17.75 inches by 24.75 inches by 0.75 inches. The True Blue measures 25 inches by 18 inches by 1 inch.
Do these filters fit furnaces and air conditioners?
The True Blue fits air conditioners, furnaces, heat pumps and HVAC units. The Simply fits air conditioners, furnaces and heat pumps, and the AIRx fits air conditioners and furnaces.
