Furnace Filters
Best 20x25x4 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 a 20x25x4 furnace filter, the Aerostar MERV 8 leads in a 6-pack with an actual size of 19.50 by 24.50 by 3.75 inches and up to 3 months of filtration. The Simply runner-up is also MERV 8 in a 4-pack, while the Filtrete, Nordic Pure and Honeywell picks are MERV 12. Check actual size first, since depth runs from 3.63 to 4.38 inches across these five.
Starting out? See the main guide: Best Furnace Air Filters
Top picks at a glance
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Best OverallAerostar Air Filter 20x25x4 MERV 8 AC9.8 View on Amazon -
Runner-UpSimply 20x25x4 Air Filter9.6 View on Amazon -
Also GreatFiltrete 20x25x4 Air Filter9.5 View on Amazon -
Also GreatNordic Pure 20x25x4 Pleated MERV 12 Air9.4 View on Amazon -
Also GreatHoneywell Home 20x25x4 MERV9.2 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. Aerostar Air Filter 20x25x4 MERV 8 AC | MERV 8 | 6-pack | — | — |
| 2. Simply 20x25x4 Air Filter | MERV 8 | 4-pack | — | — |
| 3. Filtrete 20x25x4 Air Filter | MERV 12 | 2-pack | — | — |
| 4. Nordic Pure 20x25x4 Pleated MERV 12 Air | MERV 12 | — | — | — |
| 5. Honeywell Home 20x25x4 MERV | MERV 12 | 3-pack | — | 1-year |
Aerostar Air Filter 20x25x4 MERV 8 AC
A MERV 8 pleated filter in a 6-pack, with an actual size of 19.50 by 24.50 by 3.75 inches and up to 3 months of filtration.
- MERV rating: MERV 8
- Pack size: 6-pack
Good for
- Buyers who want a 6-pack of MERV 8 filters
- Buyers who want up to 3 months of filtration
Skip it if
- You want a MERV rating above 8
- You want an actual depth above 3.75 inches
Its electrostatically charged pleated media traps particles while air flows through, and the heavy-duty beverage board frame has a moisture-resistant backing. Actual size is 19.50 by 24.50 by 3.75 inches, it fits Lennox, Carrier, Bryant, Payne and Honeywell systems, and it lasts up to 3 months.
Simply 20x25x4 Air Filter
A MERV 8 pleated filter in a 4-pack, with an actual size of 19.5 by 24.5 by 3.63 inches and up to 3 months of filtration.
- MERV rating: MERV 8
- Pack size: 4-pack
Good for
- Buyers who want a 4-pack of MERV 8 filters
- Buyers who want filters made in the USA
Skip it if
- You want a MERV rating above 8
- You want a filter compatible with Honeywell
Actual size is 19.5 by 24.5 by 3.63 inches, it works with almost any brand except Honeywell, and it lasts up to 3 months. It is made in the USA from 100% American components, including recycled materials.
Filtrete 20x25x4 Air Filter
A MERV 12 filter in a 2-pack with MPR 1550, a 12-month change interval and an actual depth of 4.31 inches.
- MERV rating: MERV 12
- Pack size: 2-pack
Good for
- Buyers who want a 12-month filter change interval
- Buyers who want MERV 12 with MPR 1550
Skip it if
- You want a MERV rating below 12
- You want an actual depth below 4.31 inches
The Filtrete is a MERV 12 filter with MPR 1550 in a 2-pack, sized 19.88 by 24.63 by 4.31 inches. It captures 50% of small particles from the air passing through it, uses 3-in-1 technology to pull in and trap particles, and fits Honeywell and AprilAire Space-Gard media air cleaners. Change it at least once every 12 months, and the Smart App sets 90-, 180- or 365-day reminders.
Nordic Pure 20x25x4 Pleated MERV 12 Air
A MERV 12 pleated filter in a 2-pack, equivalent to MPR 1500-1900, with an actual size of 19.5 by 24.5 by 3.63 inches.
- MERV rating: MERV 12
Good for
- Buyers who want MERV 12 equal to MPR 1500-1900
- Buyers who want filters made in the USA
Skip it if
- You want a MERV rating below 12
- You want an actual depth above 3.63 inches
The Nordic Pure is a MERV 12 pleated filter made with synthetic poly blend media, equivalent to MPR 1500-1900. Actual size is 19.5 by 24.5 by 3.63 inches in a 2-pack, and it is made in the USA.
Honeywell Home 20x25x4 MERV
A MERV 12 pleated filter in a 3-pack, sized 19.9 by 24.9 by 4.38 inches, with a 1-year limited warranty.
- MERV rating: MERV 12
- Pack size: 3-pack
- 1-year warranty stated
Good for
- Buyers who want a 3-pack of MERV 12 filters
- Buyers who want a 1-year limited warranty
Skip it if
- You want a MERV rating below 12
- You want a warranty longer than 1 year
The Honeywell Home is a MERV 12 pleated filter in a 3-pack, sized 19.9 by 24.9 by 4.38 inches. It fits Aprilaire and Space-Gard models 2200 and 2253, and it captures a high percentage of household airborne particles, including microscopic particles. It carries a 1-year limited warranty.
How to choose
MERV ratings and particle capture
MERV rates how well a filter captures particles, with higher numbers for finer capture. The Aerostar and Simply are MERV 8, while the Filtrete, Nordic Pure and Honeywell are MERV 12. The Aerostar and Simply each trap 90% of airborne particles, and the Filtrete captures 50% of small particles from the air passing through it.
Actual size and fit
Nominal size is not the size that fits your slot, so compare actual size before ordering. The Aerostar measures 19.50 by 24.50 by 3.75 inches, the Simply and Nordic Pure measure 19.5 by 24.5 by 3.63 inches, the Filtrete measures 19.88 by 24.63 by 4.31 inches, and the Honeywell measures 19.9 by 24.9 by 4.38 inches. The Filtrete fits Honeywell and AprilAire Space-Gard cleaners, the Honeywell fits Aprilaire and Space-Gard 2200 and 2253, and the Simply does not fit Honeywell.
Pack size and change interval
The Aerostar comes in a 6-pack and the Simply in a 4-pack, each lasting up to 3 months, while the Honeywell comes in a 3-pack and the Filtrete and Nordic Pure in 2-packs. The Filtrete lasts 12 months before a change. Count your slots and your calendar before you pick a pack.
FAQ
What MERV rating does each filter have?
The Aerostar and Simply are MERV 8, and the Filtrete, Nordic Pure and Honeywell are MERV 12.
What actual size should I check before ordering?
Check depth most of all: the Simply and Nordic Pure are 3.63 inches deep, the Aerostar is 3.75, the Filtrete is 4.31, and the Honeywell is 4.38. Length and width also vary slightly across the five.
What change interval does each filter list?
The Aerostar and Simply last up to 3 months each, and the Filtrete lasts 12 months before a change.
Which filters fit Honeywell systems?
The Aerostar fits Honeywell systems, and the Filtrete fits Honeywell and AprilAire Space-Gard media air cleaners. The Simply does not fit Honeywell.
