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Air Filter Sizes Chart

What Air Filter Size Do I Need?

Regardless of the air filter or furnace filter size you need, we have them in stock and ready to ship. Use the following size selector by selecting your filter's dimensions: width (long side), depth(short side) and thickness. You can also scroll down and use the Air Filter Sizes chart to pick the right size and quickly checkout.

Available Air Filter Sizes and Types

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

All Air Filter Sizes are Proudly Made in the USA

Filter King is a US-based manufacturer, and all our materials are produced and put together in our Alabama 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 any furnace filter size. 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 filter 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?


  • 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.

  • 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.