Best Air Filters for Your Central AC and Furnace - Consumer Reports

Hidden away in your basement or attic, the air filter in your HVAC system is something you probably don't think about much. But a good air filter keeps your central air conditioner (and furnace) humming along by protecting the mechanicals from dust and debris. And the best filters trap indoor pollutants such as dust, pet dander, and pollen, helping to clean the air in your home so it's better for you to breathe.

That's important because the concentration of air pollutants inside your home can be two to five times higher than concentrations typically found outdoors, according to the Environmental Protection Agency. An effective, snug-fitting HVAC filter can also help filter the air inside your home when air quality outdoors is poor, the EPA says.

We gauge how well an air filter removes dust, pollen, and smoke from the air, and see how freely air flows through the filter at any fan speed. We also calculate the annual costs of replacement filters, based on the manufacturer's recommendation for when to change them. (Keep in mind that prices may vary by retailer and that it may be cheaper if you buy filters in bulk.)

"We find that thicker filters have two big advantages: They filter particles out of the air better and require replacement less often," says Misha Kollontai, who oversees CR's air filter testing. But not every HVAC system can accommodate a thicker filter—the most common size is 1 inch thick—though you can retrofit the ductwork of some systems to accept one.

Something else to keep in mind as you shop is the filtering grade given by the manufacturer. The most commonly used system applies a MERV number (minimum efficiency reporting value) to each filter, which was developed by ASHRAE (formerly the American Society of Heating, Refrigerating and Air-Conditioning Engineers). But 3M and Home Depot have developed their own classification systems called MPR (microparticle performance rating) and FPR (filter performance rating), respectively. "Both types of grading assign higher values to more effective filters, so when in doubt, go with a higher rating," Kollantai says.

Don't have a forced air HVAC system? You can still get some relief with a DIY air cleaner. We tested this popular social-media hack in the lab. Here's what you need to know before trying it at home.

Below are the top air filters from CR's tests, grouped by their thickness and listed in alphabetical order. For more information on air filters, including some models to avoid, see our full air filter ratings and air filter buying guide.