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Custom Air Filters

Step 1 - Select the desired filter dimensions (height is smaller dimension)

(6 filters per case )
Please Note FAQ Close

Our custom filter sizes are currently available in depths of 1", 2", and 4". Please make sure that you enter the correct dimensions below as we do not allow returns on custom air filters. Sizes are available in increments of 1/8th of an inch, and are sold in cases of 6 filters.

When ordering a custom size filter, make sure that you select dimensions that will fit the opening. Custom filters are manufactured to the exact size that you specify (allowing for 1/8" tolerance of each side). We will prompt you if the size you select meets the dimensions of a standard size filter. Read more

Filters Fast custom filter sizes are currently available in depths of 1", 2", and 4". Please make sure that you enter the correct dimensions in the drop down boxes. X and Y sizes are available in increments of 1/8th of an inch, and the filters are sold in cases of 6 filters.

Terms: Nominal Size: The printed value of a filter dimension. (15"x20"x1")
Actual size: Actual or real sizes of filters are typically .5" less than the printed dimension or nominal value listed on the filter. A filter of 20"x24" would be 19.5"x23.5"

Step 1. Select your Merv rating. In this step you will tell the system which Merv rating you want to create your filter from. There are 3 different Merv ratings that we provide in our Custom Air Filters. Each Merv rating has specific features associated with it and how it will perform as a high efficiency filter. For more details click the "?" near each of the Merv options on the screen.

Step 2. Select the Depth of filter. Once you have selected your Merv rating you are ready to select the depth of the filter you are creating. Most common house filters are 1" in the depth or thickness. If you measure your filter to find the real thickness you will find that it isn't the same dimension as it states on the filter. This difference in the real dimension to the printed dimension are industry standards and can be confusing. The printed size on a filter is called nominal size and is not the real dimension of the filter. So a 1" thick filter is normally .75" thick. To make it easier to talk about sizes we use the nominal dimensions to refer to filter instead of the actual or real size. Because you are creating a filter by selecting the real dimensions, it is important to know the real dimensions of your filter instead of the nominal or printed dimensions that show on your filter. We will show you the nominal dimension for the Depth or thickness because there are only 1",2", or 4" sizes. Now you would select 1" for your filter if you are replacing a .75" filter, if your filter is 1.75" that would be a 2" filter and a 4" is 3.5"

Step 3. Select the Height and Width dimensions. Now it's time to specify the height and width of the your custom filter. Of the 2 dimensions the height is the smaller one. Measure that side and select the closest value in the drop down list that matches your filter. In the case of not finding an exact match, most times it's better to round down. A filter that is too big to fit in the opening or too small to stay in place, will be problematic. Now go ahead and select the width that best matches the longer dimension of your filter from the drop down list. We're almost done!

Step 4. Select the number of cases. This is the last step. Now select the number of cases that you want to order. We currently ship our custom filters in cases of 6 filters per case.

You will notice that there is a box to the right of the height and width drop down boxes that says "Custom Size". The system will alert you in this window, if you should end up defining a filter with dimensions that match one of our standard sized filters. This will also allow you to go ahead and order the standard filter by pressing the add to cart button just like adding a custom filter order to your cart. And of course you can return to this page and define more filters to order.

Ships in 5 to 7 business days.

Step 2 - Select the MERV filter performance

Customer Reviews:

Total Reviews: 275 Average Rating: 4.75 / 5.0

Filtersfast Reviews on Trust Pilot external site

Perfect fit

Collected by
Sherry Osborne2024-04-03

We love the way the filters fit. We are very pleased. We�ve been on auto ship and have too many due to the fact that we haven�t been home to change them in recent months. Need to stop that for a bit but otherwise, very pleased!

Collected by
customer Jeff2024-04-03

Cheaply made. The thinnest cardboard available. I will not order again.

Collected by

Re-ordered this filter. It fits well and very effective.

Collected by
Francisco Rodriguez2024-03-29

It's more hard and easy to install then the regular I using before

Collected by
Jason Madary2024-03-25

Good and fast services

Collected by
Arthur Lemmer2024-03-21

Filters were perfect thanks!

Collected by
Anthony Basso2024-03-19

Catches everything that comes to the furnace

Collected by
Robert Martin2024-03-18

Great price on my hard to find sized filters

Collected by

Outstanding Performance.

Collected by
Robert Bernstein2024-03-10

The filters I have ordered from you are fine and and will keep on ordering them

Collected by
Paula Shiver2024-03-07

Thank You for good service and convenient.

Collected by
Norman Brehm2024-03-05

Good quality filters made to exact size needed

Collected by


Collected by


Collected by
Charles Bishop2024-01-28

good quality and service

Collected by

Great product. Great customer service. Great company.

Collected by

It works fine but in future I could use them an inch thicker

Collected by
Robert Oesterle2023-12-31

i am not happy with the filters at all! i ad a new ac system installed, and i ordered the size filter that was in the unit at the time of purchase. well it turns out to be the wrong size that is in the unit. it states on the filter in system that it is 20 x 20 x 4 11 mrv filter. thats what i ordered. when they arrived i tried one out and it did not fit in opening. i measured the filter that i purchased and it measures 20 1/8 by 20 1/8 by 4 x1/8. i measured the filter in the unit and it is 19 x3/4 x 19 x 3/4 . it says 20x20x4 on filter. my question is what happened? since there is no returns im stuck with these filters and out $126.00. who do i blame for this?

Collected by
Scott Scholl2023-12-27

The filter is very well built and fits my dehumidifier perfectly.

Collected by
Close Healthier Indoor Air Quality

Filters Fast MERV Air Filters effectively reduces pollen, dust, pet dander, mold spores, dust mites and other allergens from indoor air. Removing these airborne particles can help improve allergies and alleviate sinus irritation that can cause watery eyes, itchy throat, coughing, and sneezing. Filters Fast Merv 8, 11, and 13 furnace filters, AC filters are now available.

Green Technology

The Filters Fast MERV air filter meets the Green Building Council's latest LEED (Leadership in Energy and Environmental Design) Indoor Air Quality Requirements for occupant health. That makes this filter a quick and efficient way to achieve points toward your company's LEED Certification. And in case you didn't know LEED certification can earn you tax breaks, which is just one way this filter can save you money!


MERV, or Minimum Efficiency Reporting Value, indicates when a filter will be least efficient. So the higher the MERV rating, the more efficient the filter. It should be noted that most fiberglass spun filters such as those found in your local grocery store are usually only a MERV 1 or MERV 2. This can affect the efficiency and air flow of your heating and cooling system, causing it to work harder to produce the same air flow and costing you more money! The Filters Fast MERV 8, 11, and 13 Filter features a low pressure drop, which means less impact on your energy use, which again will save you money!

Quality Construction and Capacity

The Filters Fast MERV 8, 11, and 13 filter is constructed of a galvanized, corrosion resistant metal support grid and 100% electrostatically charged synthetic graded density media. The media used is resistant to a wide range of chemicals and will not absorb moisture, which can support microbial growth.

The Filters Fast MERV 8, 11, and 13 filter's pleats are designed in a way to promote maximum surface area and dust holding capacity. The pleats are actually bonded to the frame to prevent any dust bypass. This means higher efficiency and air quality. These filters have 15 pleats per lineal foot which creates a greater surface area to catch airborne particles than standard filters. That also means that in most cases you don't have to change them as frequently!

Merv Chart Close Window
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