The 20x20x4 air filter is designed for residential furnace and HVAC systems, helping improve indoor air quality while protecting your equipment.
Actual size: 19.5 x 19.5 x 3.75 inches
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Check the label on your current filter or use a tape measure to determine the length, width, and thickness. Just make sure you know the difference between nominal and actual size.
Nominal Size: 20x20x4
Actual Size: 19.5x19.5x3.75
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 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 20x20x4 furnace filter or HVAC air filter is easy. 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 20x20x4 air filter is 19.5x19.5x3.75 inches. The actual size always tends to be less than the nominal size to ensure the filters easily fit into the media cabinet.
You can only use a 20x20x5 air filter instead of a 20x20x4 air filter if your HVAC system is designed to handle a thicker filter. Refer to your HVAC manual or measure the dimensions of the filter media cabinet to determine proper sizing.
20x20x4 air filters should be replaced every 6-9 months. The frequency depends on various household factors. For instance, if your household has pets, allergy-sensitive members, poor local air quality, or your system runs for extended periods, you'll likely need to replace it sooner than 9 months.
A 20x20x4 air filter may restrict airflow in your HVAC system if it's an older or lower-capacity unit. Consult your HVAC system manual to determine the proper filter size and recommended MERV rating for your unit.
Yes, 20x20x4 air filters are only designed to fit inside housings that can accommodate this specific size filter.
20x20x4 air filters are more expensive than 1-inch filters because they last longer. These filters have more surface area to trap airborne particles and contaminants. This increased surface capacity captures more pet dander, mold spores, pollen, smoke, bacteria, lint, and other common allergens and contaminants, extending filter lifespan.
No, most 20x20x4 pleated air filters are disposable and cannot be washed and reused. The only exception is if you purchase an air filter that's specifically designed for reuse.
Yes, 20x20x4 air filters typically reduce dust buildup on furniture and other surfaces throughout your property. While your air filter won't completely replace cleaning, the larger filter surface area can effectively trap dust and other common contaminants to improve cleanliness and respiratory health.
MERV 8 filters