All filters are made in the USA + Free Shipping on orders over $50

Whole House Filters

Available Air Filter Sizes and Types


Air Kontrol


American Standard






Comfort Plus

Day and Night

Electro Air


Five Seasons



General Aire














Space Gard and Aprilaire




Trion Air Bear



White Rodgers


Can't find your size? Click here for Custom Air Filters

Proudly Made in USA

Filter King is a US-based manufacturer, and all our components are produced and put together in our Alamaba warehouse right here in the USA.

Because we're confident of our high-quality premium filters, we offer a 30-day money-back guarantee on your order. If for any reason you're unhappy with your purchase, reach back to us within 30 days and we'll gladly refund you. Oh, we offer free shipping too when you order 2 or more filters packs.

Subscribe and Save: Buy More, Pay Less

Why get in the trouble of buying replacement filters every month when you can get us to do it for you? Our simple and scheduled ac and furnace filter delivery service may be what you need.

Swap your ac/furnace filter on time, every time! We have a wide variety of sizes to meet your every needs.

Questions about air filter sizes?

  • How do you measure an air filter size?

    An air filter’s size is described using three different measurements. The length, width, and depth of a filter are printed out in small numbers along the frame of the filter on the cardboard edge of a Filter King brand filter. But other filters may not have this information conveniently located, and you may need to find the measurements yourself. When doing so, check to see whether the filter is square or not. If it is not square, then the smallest-size side’s measurement goes first, followed by the next side, and then finally the depth measurement. 10x15x1 is a proper example of the correct size. From the actual sizes, round up the measurements to the nearest whole numbers when you order new air filters. This rounded measurement is referred to as the nominal size and is used to match the right filter to its fitting air filter slot. By using the nominal size, you can order a new air filter that slides in and out of place with ease.

  • What is the most common size furnace filter?

    Currently, the most common size furnace filters are 10x20. But should your system need custom sized air filters, note that we offer custom sizing ranging from 8 x 24 x 1 to 25 x 30 x 1. We even offer 3M furnace filters 20x25x1 in size.

  • What size do furnace filters come in?

    There are hundreds of variant sizes of furnace filters because air filters and furnace are both the same. The only difference between the two is location. Filter King offers hundreds of different filter sizes capable of use for several home systems, including your furnace.

  • Where is the air filter on an AC unit?

    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.

  • Can I run my AC without a filter?

    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 a filter as a gatekeeper (which really is), and its purpose is to protect both you and your HVAC system from dust and dirt, that if left unfiltered, can cause harm to both you and your HVAC unit in the long run.

  • What happens if the air filter is backwards?

    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.

  • Will dirty air filter affect AC?

    Yes, over time dirty air filters will affect AC more and more. The longer a 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 hvac 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.

  • What happens if your AC filter is dirty?

    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.

  • Are air filters important?

    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.

  • What are the symptoms of a bad air filter?

    Reduced airflow and increasing power bills are the first signs to watch out for. With a broken or old filter, your HVAC system has to work much harder to keep your house cool.

    When an air filter is bad, that can mean that it is either dirty or broken. When dirty, the symptoms include the air inside of a home drying out or stagnating and dust particles filling the air. If the air filter is broken or not working, removal ofparticles such as pollen, dust, mold, dust mites, bacteria, pet dander, smoke, mold spores, and viruses is limited, which means there is lack of cleaner air in the house.

  • How much is an air filter for House?

    The price of a single Filter King brand air filter varies depending on its measurements. However, the price falls when you buy multiple filters per order. Orders of two or more filters are also shipped for free.

  • What MERV rating should I use in my home?

    MERV ratin 8-13 is recommended for households. A good place to start would be at MERV of 8 if no one in the home has breathing issues. But for homes with pets, allergies and asthma patients, it is recommended you use MERV of 11. For home with smokers, its best to use a higher rated quality air filter in this category which is MERV 13. To learn more about MERV rating, visit this article we've put together.

  • How many air filters does a house have?

    This is entirely dependant on your home and the kind of AC system it has. Consult the homeowner’s guide for your home air system to understand how many air filters your home has and in what sizes.

  • Which should I buy, a disposable air filter or washable filter?

    Washable air filters may seem like an attractive option at a glance. There a varied opinions about the effectiveness of washable ac/furnace filters, but one thing is clear: the longer one uses a washable air filter, the less effective they become with removing smaller particles. Our recommendation? For guaranteed high indoor air quality, it's better to stick to disposable air filters.

  • What should I look for in a home filter?

    The three most important things to consider when selecting the correct filter for your home include, filter size, material and MERV rating and price. Here at Filter King, we're able to provide a wide variety of filters for your home and business with the best MERV rating and the best price.