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What Are The Most Common Air Conditioner Air Filter Sizes

Before you replace any of the filters in your home, you obviously should know what type and size you will need to buy as a replacement. Furnaces come in many different types, but most use the same furnace filter size. Yet the question of what is the most common HVAC or Air Conditioner filter size confounds many folks that call us for advice or consulting on what size filter is best for them. 

Air filters with the dimensions 16x20x1, 20x20x1, 16x25x1, 20x20x1 are all standard sizes. Almost all AC and HVAC units use standard-sized filters, yet there are some that will require a custom-sized air filter to be purchased and installed. 

However, why does the filter size even really matter? Because incorrectly sized and installed filter frames and sizes will significantly decrease the filter s effectiveness through air seepage. Additionally, if you use a filter that does not fit your HVAC unit properly, it will contribute to air flow resistance and more stress on your equipment, which can damage your system and increase your energy bills. Plus result in unnecessary costs to both fix and/or replace your unit by lowering its life expectancy.

Choosing the Correct Air Filter Size

Have you ever changed your air filter before? If so, what size did you use? Since you probably only replace it every 30-90 days (or maybe longer), you don't have to check its size every time you replace it. At the very least, write it down (along with the date!) in a place that you can't miss it every time that you change your filters. This will help you remember not only when you changed the filter, but also what size your unit requires (and even where you purchased the filter from & the price should you want).

When air filters are referred to as standard, it sounds simple enough;  you might assume that if the size is standard, you can easily find one in the store. However, that's not the always case - there are more than 20 "standard sizes" of air conditioner filters that have different measurements.

So, how do you determine which air filter size is best for you? Here are some tips to help you 

Ways to Find Your Correct AC Air Filter Size

  • Look at the Filter's Label

Take the existing AC filter out of its slot and examine the frame to determine its size. The filter sizes are usually printed along the frame's edge. The size listed in bold on the filter's frame is the filter's nominal size, which may differ from its actual size. Please double-check the filter's dimensions if they are not listed in the fine print.

  • Measure Your Filter

Any time you're in doubt, you can always measure your air filter yourself with a ruler. Whether your air filter's labelled size is not present or you are not certain of its dimensions, you can measure it by following the steps below: 

  1. Turn your AC off
  2. Measure the length, breadth, and depth (thickness) of your air filter with a ruler or another measuring equipment.
  3. For each dimension, round to the nearest whole number to figure out the nominal filter size.

    Where Can I Buy Standard Sized AC Filters?

    Within each efficiency level, most white, pleated air filters are the same -- if anything, they will differ a little depending on the brand. You can purchase air filters in a variety of ways that are convenient, whether it is; 

    • Retail Stores
    • Online Stores

    Usually, there are only 10 air filters sizes available at retail locations. 

    But when you buy filters from US Home Filter, you will never disappoint. US Home Filter makes over 80 standard stock sizes that local stores do not have enough shelf space to stock, nor do they have the inventory capacity to stock. Our company manufactures and stocks them all because that's what we do! See our full selection of air filters, from the most common 16x20x1, 20x20x1, 16x25x1, and 20x25x1 to other sizes including 8x16x1, 30x36x2, and 25x29x4. 

    Have Questions - Call US Home Filter for Answers

    There are tens of thousands of distinct air filter sizes that can be used in a heating or cooling system. Due to this, you may not always be able to find a filter in a store or online as you can find a regular stock size. If this is the case, you will need to order a custom-sized air filter. In contrast to stock sizes, custom filters are not made to a nominal size. At US Home Filter, we manufacture custom-sized filters based on the HVAC manufacturer's specifications.

    If you're still unsure, US Home Filter can help! Get in touch with us online or call us now at 855-237-1673. It is our pleasure to assist you in selecting the best filter for your needs.

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