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.

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.

Step2. 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"

Step3. 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!

Step4. 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.