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Filterking offers all main air filter types. Select from the following Air Filter Sizes below. You can select the thickness of your filter or You can select your Air Unit brand by clicking Whole House Filter. If you can’t find your size, please select Custom Filter Sizes.

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Made in the USA

Not only are all our filters proudly manufactured and assembled here in the USA, but they also comply with all FTC rules and are certified by regulatory bodies such as SafeHome™.

With the right air filters, you can protect your loved ones from harmful airborne allergens and irritants such as:

Filter Features


The general recommendation is to change your furnace filters at least every 90 days. However, this is just a generalized recommendation, and other factors come into play that can decrease the longevity of the furnace filter.

If you smoke, vape or have indoor pets, it might be better to replace your air filters every 60 days. If allergies or asthma are an issue in your household, replacing your filters every month could help keep the air cleaner, especially with a higher MERV rated filter.

Your furnace filter is located in a vent either on an interior wall or in the ceiling. The vent is usually white, but can sometimes be painted the same color of the wall. Simply pull the little level on the side to open the vent. Remove the old filter and replace the new furnace filter.

When you change your air filters depends on the indoor air quality levels you want to achieve. While Filter King filters can last 90 days, you may want to change them sooner. There are several factors that go into when you might want to switch out the current furnace filter. If you have allergies or asthma, a fresh filter can help with indoor air quality. If you have pets or smoke, then changing air filters sooner than 90 days can keep the air quality fresher.

Depending on your AC unit, the air filter slot may be located in a hard to find location. First, try checking the blower compartment or return air duct where the air is cleaned before going through the unit. The unit itself may have the air filter inserted in a specific location.

Yes, but it is not recommended that you do so. There are several issues that occur for an AC unit, your home air system, and the home itself when an air filter is not installed. Think of an air filter as a gatekeeper (which really is), and its purpose is to protect both you and your AC system from dust and dirt, that if left unfiltered, can cause harm to both you and your AC unit in the long run.

Air filters are built with a tight mesh weave that is designed to capture and absorb incoming particles. Air is brought through the porous side, and the mesh weaving allows it to flow in and out while being cleaned. When backwards, air has a harder time coming through, which means the system will require more energy to push it through, and thus affecting the quality of air filtration. When an air system is strained like this, it causes a rise in home energy billing and possible mechanical damage.

Yes, over time dirty air filters will affect AC more and more. The longer an air filter is left in a system, the dirtier it becomes, and the more pronounced the effects will be. There are many factors that determine how long an air filter can last such as the type of filter, material, home size and daily habits. The higher the FPR rating system (developed by Home Depot), the longer the filter lasts. MERV rating is another popular rating system used both locally and internationally.

When your air filter is dirty, the mesh wearing that it consists of becomes clogged and full of dirt and debris. When this happens, the air that is supposed to flow forward through the filter has a harder time passing into the air system. The system will use more energy to try and push the air forward, straining itself and raising your energy billing in the process. The air inside your home may also start becoming stagnant and dirt over time since fresh air is unable to come in.

Yes, they are very important to any air system they are in. Air systems have no way of knowing whether the air they are bringing in is clean or dirty. Air filters are essential to making sure that any air brought in is cleaned before entering the system. Without filtration, the air coming in from outside may contain any number of dust, debris pollutants, and allergens.

Air Filter Basics

What Are HVAC Filters?

HVAC is an acronym for "heating, ventilation, and air conditioning." An HVAC is a system that provides both heating and cooling to residential and commercial buildings. The ventilation function in an HVAC system uses a furnace filter to clean the indoor air and replace it with fresh air from the outdoors; this removes anything in the air ranging from smoke, dust, moisture, and undetectable gases that decrease ambient air quality.
Learn more about HVAC

What Is MERV Rating?

MERV stands for Minimum Efficiency Reporting Value. In short, a MERV rating lets you know what air particle size an air filter will trap. A higher rating means that the filter can trap smaller air particles.
Learn more about MERV ratings

Dirty-Clean Filter

Keep Your Home Clean and Allergen Free With Our AC/ Furnace Filters

Clean air should never have to be something you worry about. Approximately 1 in every 7 Americans has respiratory issues such as Asthma and COPD. Maintain a healthy home environment for your loved ones today.

Don’t Take It From Us...Our Customers Say It Best

Terence H.
Verified Buyer
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Love the service!

Quick shipping. The option for the custom sizes I need due to the odd shape of my ductwork, is a life saver. There was an issue with my most recent order and filterking bent over backwards to make it right. Thank you!!

Verified Buyer
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Great quality and perfect fit

Great fit and excellent quality. The filter is very well made and looks like they actually take time in the making of it. Its not flimsy like other companies I've ordered from.

charles k.
Verified Buyer
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Filters work great received 2-boxes

Filters work great received 2-boxes of 6 each total of 12 great price, also brought 1-box of 12 9x11x1 filters for our dehumidifier they work great also. thanks chuck

Verified Buyer
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cleaner air

my size filter is unique and I'm glad to have such quality custom filters. compared to what is supplied by my building I now have filters that are as good as an air cleaner.

Shop By MERV Quality to Shop By MERV Rating

Filter King makes a variety of MERV-rated standard filters for all commercial and residential HVAC systems, and we can also manufacture custom-sized filters on request.


Good: MERV 8 Filter

At a minimum, MERV 8 filter can be appropriate for most residential homes. It can block up to 90% of airborne contaminants such as dust, mold, and pollen. Recommended for use in basic and standard homes and businesses.


Better: MERV 11 Filter

MERV 11 filter is a mid-level filter, a step higher than MERV 8, and can remove a much higher percentage of contaminants including pet dander and allergens. Its recommended for homes with pets and people with mild allergies or anyone looking for further filtration.


Best: MERV 13 Filter

In addition to filtering everything that MERV 11 filter can, MERV 13 air filter can filter out smoke, smog, and virus carriers. MERV 13 provides the highest level of filtration and is suitable for homes with people that smoke, have severe allergies, asthma, and other respiratory issues.


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Customers who join us today for air filter delivery subscription service will get $5 off for their first and ongoing orders.