120+ Standard Size Furnace Filters and AC Filters. 70,000+ "Exact Fit" Filter Sizes. Free Shipping on all orders.

When was the last time you replaced your furnace or air filter?
Before switching the "on" button, your home's furnace filter should be inspected and replaced. Your furnace will run more efficiently and your indoor air can be improved by replacing your furnace filter on a regular basis. The cost of replacing your furnace filter on a regular basis vs the damage that can be caused by a dirty furnace filter makes it a simple choice.


What is the difference between Furnace Filters and Air Conditioner Filters?
There is no difference between furnace filters and air conditioner filters. If a filter is listed as a furnace filter it can also be used in a air conditioning system. More often than not they are referred to as furnace filters. Other terms you may come across are HVAC filters, home air filters, pleated furnace filters, basic fiberglass furnace filters and more. Your main concern should be the filter size and how well you would like to improve indoor air quality (IAQ).


Can't find your filter size anywhere?
Are you having a tough time finding your filter size? We can help by making you custom furnace filters to your exact size. Custom furnace filters provide the filtration and protection you need. The primary purpose of furnace filters are to protect your system, so with out a properly fit air filter the protection won't be sufficient. Custom furnace filters and AC filters will help protect your system and improve your indoor air quality.

AAF Flanders

All filters are manufactured in the US by AAF Flanders, the largest air filter manufacturer in the country. We have been a trusted retailer of AAF Flanders filters for 10+ years and are a recommended retailer for buying direct. AAF Flanders filters are selected for their quality and value by organizations that require the cleanest air possible, including NASA and hospitals.

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Common Filter Questions

Where is my filter located?
Your filter can be located anywhere between the furnace and the where warm or cool air enters the room. Common locations include inside the ductwork, behind vents or in the air handler itself.


What size filter do I need?
Most furnace filters have two sets of dimensions; nominal and actual. If you measure your filter and it's actually 15 1/2" x 24 3/4" x 3/4", you would round up and search based on the nominal dimensions of 16" x 25" x 1". If the nominal size isn't printed on your old filter just measure your filter width, length and thickness. Round up and you'll get the nominal size. We always recommend measuring your filter just to be sure.


Custom size filters
When ordering custom filters submit the exact size down to 1/8" you would like us to make your filters. Please don't submit the nominal size (rounded size) of the filter, submit the actual exact size.

Commercial Programs

Commercial Buildings, Restaurants, Retirement Communities, Gyms, Schools, Apartments, Condos...We will work with you to develop a filter program that best suites your building needs. 

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MERV Rating (Minimum Efficiency Reporting Value)

Minimum Efficiency Reporting Value (MERV) is a filter industry standard system that rates the overall effectiveness of air filters. Higher value MERV rating equates to finer filtration, meaning fewer dust particles and other airborne contaminants can pass through the filter. Other common ratings found within certain brands and stores includes FPR, MPR. They all follow the same basic principal, the higher the number the greater overall effectiveness of the air filter.

Some of the common particles that filters are tested for include pollen, dust mites, textile and carpet fibers, mold spores, dust, pet dander, bacteria and tobacco smoke.