Actual size: 19.5 x 23.5 x 3.75 inches
Deep pleated air filters for whole-house and commercial HVAC systems
MERV 13 filters remove up to 98% of common particles including bacteria and virus carriers. These hospital-grade filters protect family members with allergies, asthma, or weakened immune systems.
Processed quickly, ships fast, free for all orders
Premium quality products crafted right here at home
Return your items within 30 days and get a full refund
Find your perfect fit with our complete size range
MERV 13 filters are ideal for homes where air quality is a top priority. They're ideal for households with allergies, asthma, and respiratory issues. Using a MERV 13 filter can also help improve indoor air quality in households with immunocompromised family members and homes with pets that require extra protection.
Our MERV 13 filters are suitable for urban homes near traffic and light commercial spaces, such as offices or medical waiting rooms and even clinics in some instances. Shared living spaces and rental units may benefit from MERV 13 filters, as the filter is designed to capture even more particles than alternative ratings.
Scroll right to see more
Check the label on your current filter or use a tape measure to get the exact length, width, and depth before selecting your size.
Nominal size
Nominal size is what you normally see printed on the label. This is usually a rounded size which is often not the true size of your filter.
Actual size
Actual size is the true size of the air filter, usually written in smaller font below the nominal size.
Measure your current air filter or the length, width, and depth of the opening slot to get the actual size. Round it up to the nearest whole inch to get the nominal size.
Installing 20x24x4 air filters couldn't be easier. Just make sure to align the arrow printed on the side with the airflow direction!
Remove the air filter from the package
Locate the arrow and point it in the direction of the fan
Slide the filter in to the slot of the central unit
For return grills, insert the filter into the grill, pointing the arrow inwards
Keeping your air filter replacement schedule in mind can be challenging to say the least. Make your life easier with Filter King's auto delivery.
The actual size of a 20x24x4 air filter is 19.5x23.5x3.75. The actual, or exact, size is always slightly smaller than the nominal size to ensure the filter fits easily into the media cabinet.
Only use a 20x25x4 filter if your HVAC system is designed to handle a thicker filter size. A 20x25x4 air filter is 1 inch larger than a 20x24x4 filter, so it won't fit into a slot designed for a 20x24x4 filter.
Replace your 20x24x4 air filter every 6 to 9 months, depending on your household's conditions. Pleated 4-inch-thick filters offer more surface area to capture contaminants and last longer than 1-inch filters. However, homes with pets, allergy sufferers, or in areas of poor environmental air quality will likely need to replace the filter more frequently.
A 20x24x4 MERV 13 air filter isn't likely to restrict airflow in modern, high-efficiency HVAC systems. However, you may notice weaker airflow in older systems that aren't designed to accommodate MERV 13 air filters.
Yes, you'll need an HVAC unit with a housing that's designed to accommodate a 20x24x4 air filter.
Vacuuming a 20x24x4 air filter to extend its life is not recommended. While vacuuming can remove surface debris, it cannot remove any particles that have become trapped in the filter's fiber. Moreover, vacuuming the filter can damage it and cause performance issues.
20x24x4 air filters are just as easy to install as a 1-inch filter. All filters are designed to slide easily into the housing, creating a snug seal without any gaps.
A 20x24x4 air filter can help household members with seasonal allergies if it has the right MERV rating. 20x24x4 MERV 13 filters are ideal for households with allergy sufferers, as they capture up to 98% of common particles. This includes dust mites, pollen, pet dander, lint, mold spores, fine dust, smoke particles, bacteria, and more.
MERV 8 filters