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Atomic Filters Carriers an Extensive Collection of MERV 8, MERV 11 and MERV 13 Replacement Furnace Filters also known as Air Filters, Air Conditioner Filters, AC Filters or HVAC Filters. We carry a large variety of common and hard to find Air Filters Sizes. If you need a custom size contact us and we can make most sizes in 48 hour turn around time (business days). Atomic has Original Equipment Manufacturer (OEM) Brands including top name brands from Carrier Enterprises. Carrier Brands include Payne, Toptech, Carrier, and Bryant. We carry the Germicidal Air Purification Filters from Carrier known as the Carrier Infinity air cleaner model or GAPA filters. 

Find Your Furnace Filter Easily

Enter The Filter Part Number or Size from Your Current Filter in the Search, for examples, enter X6670 or 16x20x1 MERV 11, or 16x25x1 to see results.


Lennox Furnace filters are among the best filters made and Atomic has a full selection of Lennox air conditioner filters. We carrier Lennox Carbon Clean and Healthy Climate Pureair System Annual Maintenance Kits.  An extensive selection of brands and compatible replacements for Amana, Five Seasons, York, Totaline, Goodman, Electric-air, Honeywell, Air Bear Trion, and Aprilaire are all available. Save money on your furnace filters without having to drive all over town to Homedepot, Lowes or Walmart. Atomic Filters delivered to your door so that you can spend your time on activities you enjoy. 

Avoid this Common Mistake and Get the Correct Furnace Filter Size

The Most common mistake made when ordering filters are ordering the wrong size furnace filter. This is because the size on the filters is not necessarily the actual size of the filter. Filters are sold by nominal sizes which are rounded sizes and usually vary by brand. You can usually Find the Size of Your Air Conditioner filter right on the size of the frame of the filter. The Picture of this 12x12x1 inch air filter has the Nominal size which is the size by which air filters are generally sold. On the right of the filter, it also includes the actual size of the filter which are the true measures dimensions of the filter by length width and depth. See air filter image:

Complete List of Furnace Air Conditioner Filters by Size


If there is no size on your current AC filter, you can measure the length, width, and depth of the filter and the filter to find the Actual Size of your filter with the Corresponding Furnace Filter size in the Furnace Filter Size(Nominal Size) Chart. 

Subscribe and Save: When you find the filter you need, choose our subscription option and save 5% on most filters. You will not only save money but also your time. Your filters will be delivered automatically based on the schedule you choose. If you move or go on vacation you can swap out your login make changes to your subscription. You can pause a filter subscription or swap out a product and change the frequency of your order.

Find Your Filter Sizes Easy choose 1" Deep Filters , 2" Deep Filters,  or 4" Deep Filters 

Nominal Vs. Actual Sizes: Finding the Right Air Filter Size

Buying the Correct Size Air Filter- The Most Important Thing to Know 

When you are buying your air filter online most important thing to know is Air Filters have two sizes that you need to understand the Nominal size and the Actual Size. Not understanding these numbers often leads to consumers purchasing a filter that does not fit their Furnace or HVAC system.

Nominal vs Actual air filter size by Atomic


Understanding Nominal Filters Size Could Save You Time and Money

Not understanding the Nominal Filter Size is the primary culprit for incorrectly purchased filters.The Nominal Size is the usually the dimensions used to Label the filter. For instance 16x20x1. These dimensions are a rounded value on the filters actual measurements. The actual measurements on this filter may be 15.5x19.5x.75, but that could vary by brand and manufacturer. So in order to make sure you have the correct size filter, especially if you are replacing with a different brand it is important to confirm the actual size on the filter. When purchasing filters on the internet the Nominal size is usually found in the product title.

Actual Filter Size- The Key to Making the Right Replacement Filter Purchase

The actual size as you might have guessed are the actual dimensions of the filter by length, width and thickness. This size is often on the filter right below the Nominal size and is usually labeled as the actual size. When you are buying a filter online the actual size is sometime in the product bullet point or the product description. If your filter does not have actual dimensions on the outside of the filter, you can measure you filter to get the correct dimensions. Some brands have a foam gasket on the outside of the filter, in this case, you will want to make sure you have a compatible actual size and that it also has the foam to ensure a snug fit. 

Lennox Air Filter X0851 with Foam strips

Examples of Nominal and Actual Sizes

 Size  Example 1  Example 2
Nominal Size 20x20x1 16x20x1
Actual Size 19.5x19.5x.75 15.75x19.75x.75


 Furnace filters should fit securely but should not have to be forced into position. If you have to force the filter into its slot, then it is probably too big. Forcing an improper filter size in a filter can cause it to buckle, damaging the filter or reducing its ability to function properly. Filters are a smaller than their slot to allow for easy replacement. Some HVAC units may need a filter with dimensions that are unique or uncommon. In these cases, a custom filter needs to be ordered.

Find Your Filter Sizes Easy in 1" Deep Filters , 2" Deep Filters, 4" Deep Filters