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Atomic FC200E1011 20x20x4 MERV 13 Honeywell Replacement Furnace Filter - 2 Pack

Size Guide

Atomic replacement for Honeywell FC200E1011 20"x20" Media AC Filter is a high efficiency Media Air Filter that can be used in Honeywell 20 x 20 Air Cleaners. This is a genuine Atomic replacement for Honeywell air conditioning filter.Honeywell FC200E1011 Specifications: Nominal Size: 20" x 20" x 4 3/8" Actual Size: 19 7/8" x 19 7/8" x 4 3/8" MERV 13 Rating Replaces FC35A1019 / 203721 Fits Honeywell Series: F25, F35, F100, and F150. The Atomic FC200E1011 20x20x5 utilizes triboelectric technology, to helps increase the filters High-Efficiency Media Air Cleaners. This air conditioner filter should be replaced at least once per year for maximum efficiency. Filter life based on air quality.

The Atomic FC200E1011 Media Filter 20x20x5- Merv 13 is a replacement air filter for the Honeywell 20X20 F100 and Honeywell F200 media air cleaners. This air filter removes over 97% of 3.0-10.0 micron particles from the air.

  • Nominal Size: 20" x 20" x 4 3/8"
  • Actual Size: 19 7/8" x 19 7/8" x 4 3/8"
  • MERV 13 Rating
  • Replaces FC35A1019 / 203721 Fits Honeywell Series: F25, F35, F100, and F150

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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. See the complete list of Air Filters by Size Rating and Brand.

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