The best air conditioner air filter is one that matches your system’s required size and filtration level. Filtrete’s 20-by-25-inch six-pack is best for basic dust defense in a compatible HVAC system, while the Amazon Basics MERV 11 filter offers a higher listed filtration rating in a 20-by-20-inch size. Simply and Frost King provide options for different filter formats and needs. Check your unit’s specifications and the filter’s actual dimensions before buying.
| Product | Best For | Key Detail |
|---|---|---|
| Filtrete 20x25x1 MERV 5 | Basic household dust defense | Six pleated filters |
| Simply 20x20x1 MERV 8 | Dust, pollen, and pet dander | Six-pack; actual size 19.75 x 19.75 x 0.75 inches |
| Frost King Foam Filter | Air conditioners that use washable foam | 15 x 24 inches; open-cell foam |
| Amazon Basics 16x20x1 MERV 8 | Common 16-by-20-inch filter slots | Six-pack; captures dust, lint, and pollen |
| Amazon Basics 20x20x1 MERV 11 | Buyers seeking a higher MERV rating | Six-pack; actual size 19.75 x 19.75 x 0.75 inches |
Filtrete 20x25x1 MERV 5 Air Filter
This six-pack of pleated filters is best for homeowners whose furnace or air conditioner requires a 20-by-25-by-1-inch filter and who want basic particle capture. Filtrete lists the filter as MERV 5 and MPR 300, and describes it as designed to capture household dust and lint.
The listed actual size is 19.69 x 24.69 x 0.81 inches, which differs from the nominal 20 x 25 x 1-inch size. Choose this option if those actual dimensions match your filter slot. It may not be the right choice for buyers seeking a higher MERV rating or a different size.
Simply 20x20x1 MERV 8 Filter
Simply’s six-pack is best for buyers with a compatible 20-by-20-inch slot who want a MERV 8 filter for dust, mold, pet dander, and pollen. The product description also lists MPR 600 and says its pleated design has a higher pleat count than most retail filters.
The stated actual dimensions are 19.75 x 19.75 x 0.75 inches, so check your existing filter or system requirements rather than relying only on the nominal size. The listing claims the filter traps 90% of airborne particles, but this product is not the best match if your system requires a different size or filter type.
Frost King Open-Cell Foam Filter
This Frost King filter is best for an air conditioner designed to use a foam filter rather than a standard pleated HVAC filter. The product information describes it as washable open-cell foam and lists dimensions of 15 x 24 inches. Its format makes it a different option from the one-inch pleated filters in this list.
Confirm that your unit calls for this style and size before choosing it. The provided product details do not specify a MERV rating or provide further filtration performance information, so avoid selecting it when you need a particular rated HVAC filter.
Amazon Basics 16x20x1 MERV 8 Filter
This six-pack is best for households whose HVAC system takes a 16-by-20-by-1-inch filter and whose needs include capturing lint, dust, and pollen. The filter has a listed MERV 8 rating and electrostatic construction. Its beverage board frame and wire mesh support are described as durable construction features.
Use the product’s actual dimensions, 15.75 x 19.75 x 0.75 inches, to check fit. It is a practical size-specific option, but it is not suitable if your system requires a 20-by-20-inch filter or another dimension.
Amazon Basics 20x20x1 MERV 11 Filter
This filter is best for buyers with a compatible 20-by-20-inch slot who want a higher listed MERV rating than the MERV 8 options here. The six-pack is described as capturing household irritants such as lint, dust, and pollen. Its beverage board frame and wire mesh support are also listed product features.
Its actual dimensions are 19.75 x 19.75 x 0.75 inches, not a full 20 x 20 x 1 inches. Check your HVAC manufacturer’s filter requirements before choosing a MERV 11 filter; the product details do not establish that it is suitable for every system.
Buying Guide: How To Choose An Air Conditioner Air Filter
What size filter does your system need?
Look for the size printed on the old filter or specified in your air conditioner or furnace documentation. Nominal dimensions are rounded labels; actual dimensions can be smaller. Compare both measurements with the available filter slot, especially when a product lists an actual size such as 19.75 x 19.75 x 0.75 inches.
Which filtration level should you choose?
MERV ratings help describe a filter’s particle-capture performance. The products here range from MERV 5 to MERV 11. A higher rating is not automatically the best fit for every system. Follow the HVAC manufacturer’s recommendations so the selected filter suits the equipment’s requirements.
Do you need a pleated filter or foam?
Pleated filters are common in residential furnace and central HVAC slots. The Frost King option is open-cell foam and is intended for units that use that kind of filter. These formats are not interchangeable by default. Match the replacement to the filter design your unit requires.
How often should you replace the filter?
Follow the instructions for your filter and HVAC system. Check the filter regularly, since household conditions and system use can affect how quickly it collects particles. Replace or clean it as directed; the Frost King product is described as washable, while the other options listed are pleated filters.
Frequently Asked Questions
Can I use any air filter in my air conditioner?
No. Match the filter dimensions and type to your unit’s requirements. A filter that does not fit correctly or is not the required style may not be suitable.
What does the actual filter size mean?
Actual size is the filter’s measured dimension. It can be smaller than the rounded nominal size printed in a product name, so check it against your filter slot.
Is MERV 11 better than MERV 8?
MERV 11 is a higher filtration rating, but the right choice depends on your system’s requirements. Check the HVAC manufacturer’s guidance before selecting a higher-rated filter.
Are these filters for vehicle air conditioning?
Most products in this article are for home HVAC systems. A vehicle cabin air filter is a separate product type and must match the vehicle application.