Best HVAC Filters by Size
Finding the right filter size is step one. Step two is picking a filter that actually works at that size. Not every brand makes every size, and quality varies wildly even within the same brand. Here’s our size-by-size breakdown with top picks for each.
How to Find Your Filter Size
🏆 Factor Filter — Every Standard Size in Stock
Factor Filter ⚡ Patented carries every standard residential size in MERV 8, 11, and 13. Made in the USA, factory-direct pricing, no middleman markup. Ships in cases for the best per-filter value. If you know your size, they probably have it.
Shop at Factor Filter →Pull out your current filter and look at the label on the frame. You’ll see three numbers like 16x25x1 or 20x20x4. That’s length × width × depth in inches. If there’s no label, measure the filter yourself—round to the nearest inch. The “nominal” size (what’s printed) is always slightly larger than the actual dimensions. A 20x25x1 filter actually measures about 19.5 x 24.5 x 0.75 inches.
16x20x1 — The Most Common Size
This is the single most popular residential HVAC filter size. If you live in a standard 3-bedroom home built after 1990, there’s a good chance this is your size.
Filtrete 1500 MPR (MERV 12)
3M’s Filtrete line is the most trusted name in home air filtration for good reason. The 1500 MPR captures dust, pollen, mold spores, and pet dander without choking your HVAC system. It’s electrostatically charged to attract particles rather than just blocking them, which means better filtration with less airflow restriction. Replace every 90 days.
Check Price on Amazon →Nordic Pure MERV 12 Pleated
Nordic Pure quietly makes some of the best filters on the market at prices below the big brands. Their MERV 12 pleated 16x20x1 consistently tests well for particle capture and airflow. Sold in 6-packs, bringing the per-filter cost down to around $8-10. Hard to beat.
Check Price on Amazon →16x25x1
Another extremely common size, especially in homes with larger HVAC returns or ducted systems.
Honeywell Elite Allergen MERV 13
Honeywell’s Elite Allergen filter is one of the few 1-inch filters we trust at MERV 13. Most MERV 13 filters in a 1-inch depth create too much static pressure, but Honeywell uses a denser pleat pattern that maintains airflow. If you have allergies, this is the one to buy.
Check Price on Amazon →20x20x1
Common in smaller systems and apartment HVAC units.
Aerostar Pleated MERV 11
Aerostar is an underrated brand that makes solid pleated filters at fair prices. Their MERV 11 captures pollen, dust mites, and mold without restricting airflow. Available in bulk packs of 6 or 12, and they ship fast. For a 20x20x1, this is our go-to recommendation.
Check Price on Amazon →20x25x1
Standard in larger homes and many 4-ton+ HVAC systems.
Filtrete 1900 MPR (MERV 13)
The 1900 is Filtrete’s highest-rated 1-inch filter. It captures bacteria, viruses attached to particles, and smoke particles in addition to standard allergens. We only recommend MERV 13 at this size because the 20x25 return has enough surface area to handle the restriction. Check that your blower can handle it—most modern systems can.
Check Price on Amazon →20x25x4 — The Deep Pleated Option
If your system takes 4-inch filters, you’re lucky. These last 6-12 months, have way more surface area, and filter better than any 1-inch filter can. The upfront cost is higher, but the annualized cost is often lower.
Honeywell FC100A1037 (MERV 11)
The gold standard for 4-inch residential filters. This is the OEM filter for Honeywell’s F100 and F200 filter cabinets, but it fits most 20x25x4 housings. Lasts up to 12 months, which means one filter change per year. The deep pleats provide MERV 11 filtration with minimal pressure drop.
Check Price on Amazon →Nordic Pure MERV 12 (20x25x5)
If your housing takes a 5-inch filter (like Honeywell or Lennox cabinets), Nordic Pure’s MERV 12 deep pleat is outstanding. Better filtration than the OEM at a lower price. Fits Honeywell, Lennox, and Carrier 5-inch housings.
Check Price on Amazon →Less Common Sizes
If your filter is an unusual size (14x20x1, 14x25x1, 12x24x1, etc.), your best bets are Filtrete and Nordic Pure—both offer the widest range of sizes. Avoid buying a filter that’s close but not exact. Even a half-inch gap lets unfiltered air bypass around the edges, defeating the purpose entirely.
Now that you know your size, read our MERV rating guide to understand exactly what level of filtration you need. Or if you have pets or allergies, jump straight to our allergy & pet filter recommendations.