How to Choose a Furnace Filter

Furnace filters keep your HVAC unit running efficiently by removing dust and particles from the air. Particles in the air can cause buildup in your HVAC unit which can lower performance and cause costly repairs. Furnace filters also have an added benefit of cleaning the air making it easier for you to breathe. To improve your air quality and prolong the life of your furnace, you need to choose the proper fitting furnace filter and change it regularly.

Steps for Choosing the Right Furnace Filter

1. Identify the Proper Filter Size

Find your existing filter size by checking your manual or looking at your existing filter. You should see a few numbers that look something like 20x25x1. This is the size of the replacement filter you’ll need to purchase. The numbers are dimensions that indicate the width, height, and thickness of the filter.

2. Choose the Right Filter Type

There are many different types of filters available. Your choices include pleated/non-pleated, disposable/washable, paper/fiberglass, and much more. The most common types of filters for households are disposable and pleated. Disposable filters are typically made of paper filters and have the added convenience of not needing to be cleaned. Simply toss and replace. Pleated filters have more surface area and remove more particles from the air than most fiberglass non-pleated filters. They also have the ability to remove much smaller particles.

3. Pick your Efficiency Rating

When choosing your right filter, it’s important to know the filter’s efficiency rating. This rating is called MERV. MERV actually stands for Minimum Efficiency Reporting Value. MERV measures the number of particles that are removed from the air, how efficient air flow is through the filter, and how long the filter should last. Simply explained, the higher the value, the more efficient the filter is at removing particles and contaminants from the air. The most common MERV rating for households is 8, but if you have pets or live in a dusty environment, you may want a higher rating of 10 or 12.

Use the chart below or see our filter recommendations to help you choose which air filter is right for you.

HVAC Filter MERV Rating Chart

MERV RatingFiltered ParticlesTypes of Filters
1-4 Carpet fibers, spray paint dust, sanding dust, dust mites, pollen Disposable Filters – fiberglass or synthetic
Washable – aluminum mesh
Electrostatic – woven panel filter
5-8 Mold spores, hair spray, pudding mix, cement mix Pleated Filters – disposable, thick with cotton-polyester blend media
Cartridge Filters – synthetic media
Disposable – synthetic panel filter
9-12 Legionella, humidifier dust, lead dust, milled flour, auto emissions, welding fumes Box Filter – Cartridge 6-12″ deep lofted or paper media
Bag Filter – nonsupported microfine fiberglass or synthetic media 12-36″ deep, 6-12 pockets
13-16 All bacteria, most tobacco smoke, Proplet Nuclei (Sneeze) Box Filter – Cartridge 6-12″ deep lofted or paper media
Bag Filter – nonsupported microfine fiberglass or synthetic media 12-36″ deep, 6-12 pockets

4. How to Replace your Filter

HVAC systems in your home vary but there will be an access panel for you to change the filter. If you have a forced air unit, you might find the filter access panel in a wall or ceiling. For indoor furnaces, the access panel is typically located on the unit. It is common to need to loosen a few screws to remove the panel, so have a screwdriver handy.

5. How Often to Change your Furnace Filter

Most filters have a recommended time to change the filter of around 3 months. While this is a good rule of thumb, all households are different. If you have pets, carpet, or a very dusty environment, expect to change your filter more frequently often monthly. If you are unsure if the filter needs changing, simply take a look at it. A good visual indicator is if the filter has darkened in color and is completely covered with dust. If your filter looks like that, its time to change it.

Remember, a proper fitting and clean filter are essential for your furnace to run efficiently and prolong the life of the unit.

Visit our Amazon store for a list of our recommended filters and cleaner for your HVAC unit.