How to Measure Your Filter
Steps 1 & 2
Measuring Length and Width (L x W). (If your filter is not a square, the smallest measurement goes first).


Step 3
Measure the thickness (Depth) of your filter from front to back.

Step 4
Put Your measurements together (L x W x D).

Actual Size
A filter’s true dimensions.
Example: 19.75” x 19.75” x 1”
Nominal Size
Rounded numbers used by manufacturers.
Example 20” x 20” x 1”
View Detailed InstructionsAbout 20x20x4 Commercial HVAC Air Filter
The Aerostar 20x20x4 commercial HVAC air filter is ready to filter the air in your home or office. Choose the MERV rating that suits your lifestyle and start filtering cleaner air through your air conditioning or furnace system.
Fights lint, dust mites, mold spores, pollen, pet dander, and dust.
Every 60-90 Days
Qualifies for Free Shipping
Pleated MERV 8 Media
Comparable to MPR 600 and FPR 5
Designed for Superior Filtration Efficiency
Made with electrostatically charged synthetic material that draws and captures allergens between 3 - 10 microns, including lint, dust mites, mold spores, pollen, pet dander, and dust.
Improve Indoor Air Quality
Protect your family and loved ones with clean indoor air quality at home. Aerostar filters are a simple and cost effective step towards a healthier home environment, free of airborne allergens and particles that can trigger various allergy and asthma symptoms.
Improve Efficiency and Reduce Cost
An Aerostar furnace air filter helps keep your HVAC unit working efficiently by removing dirt and reducing strain on the motor. When your unit runs properly, it consumes less energy, requires less maintenance and will have a longer life. These factors will have an impact on your utility bill and maintenance costs. It is recommended that you change the filter every 60 to 90 days during normal times of year but increase frequency to 30 days during peak summer and winter months when your unit is working the hardest.
About Aerostar Furnace Air Filters
Aerostar filters are manufactured in the USA by Filtration Group, a world-leading manufacturer and supplier of filtration solutions for residential, commercial and industrial applications. The Aerostar brand is known for constantly innovating and improving their technology to help make filtration more efficient, effective and environmentally friendly every day.
About MERV, MPR and FPR Rating
The three rating systems were created by different organizations. MERV is the domestic and international Industry Standard rating system established by the American Society of Heating, Refrigerating, and Air Conditioning Engineers. The other two rating systems were created by 3M and The Home Depot, but all are rating the same filter.
MERV Rating (Minimum Efficiency Reporting Value): As you have already learned, the MERV Rating is the primary rating system used in the industry, both domestically and internationally. Established by the American Society of Heating, Refrigerating, and Air Conditioning Engineers, MERV rates a filter’s ability to capture and hold particles and pollutants.
MPR (Micro-Particle Performance Rating): MPR Rating is a rating system developed by 3M. It rates the manufacturer’s Filtrete product line and their ability to capture airborne particles smaller than 1 micron.
FPR (Filter Performance Rating): FPR Rating is a rating system developed by The Home Depot for brands sold through their stores, including Honeywell. It utilizes a color code and number scale (4 to 10) that closely resembles the MERV rating.
What is a MERV Rating?
MERV ratings let you know the efficiency and level of filtration that an air filter can handle under normal circumstances. The higher the MERV rating, the finer the particles are that are filtered our of the air in your home. Many air filter retailers use MERV or a similar rating to rate their air filters.

About MERV, MPR and FPR Rating

MERV Rating is the primary rating system used in the industry, both domestically and internationally. Established by the American Society of Heating, Refrigerating, and Air Conditioning Engineers, MERV rates a filter’s ability to capture and hold particles and pollutants.

MPR Rating is a rating system developed by 3M. It rates the manufacturer’s Filtrete product line and their ability to capture airborne particles smaller than 1 micron.

FPR Rating is a rating system developed by The Home Depot for brands sold through their stores, including Honeywell. It utilizes a color code and number scale (4 to 10) that closely resembles the MERV rating.
FAQs
An Aerostar 20x20x4 furnace filter is designed to work inside commercial HVAC systems and is built for efficiency. Due to its deep pleated structure, thick design, and large surface area, it can keep a range of pollutants out of large spaces and ensure cleaner air will circulate. Its durable construction is ideal for businesses that need reliable and superior air purification.
In commercial settings, a 20x20x4 air filter should typically be replaced every 60 to 90 days, but the time involved might depend on system usage and the level of airborne contaminants in the environment. Businesses that experience higher foot traffic, like offices, retail stores, hotels, and hospitals, will probably be circulating a higher volume of pollutants, dirt, and dust throughout their HVAC system. Large warehouses and manufacturing facilities might need to have their filter replaced each month if airborne grease, dust, or industrial debris causes their filter to clog up. When HVAC systems run continuously like they do in industrial areas, having a facility manager examine the filter every month will ensure it keeps working and delivering steady airflow. When filters aren’t replaced on time in commercial buildings, it leads to poor air quality, employee discomfort, increased energy costs, and potential damage to HVAC systems.
When you want to select the right MERV rating for a 20x20x4 filter, business owners should think about their HVAC system’s capacity and the specific indoor air quality their commercial business needs. A 20x20x4 MERV 8 air filter effectively catches dust, pollen, and lint while circulating air efficiently. When your business needs more filtration than a MERV 8 filter offers, a 20x20x4 MERV 11 filter is effective for trapping mold spores. To achieve the highest level of filtration, a 20x20x4 MERV 13 captures bacteria, microscopic contaminants, smoke, and fine dust particles that might be circulating in your office or business. Prior to picking out a higher MERV-rated filter, make sure your building’s HVAC system can use one with increased density by checking its specifications.
20x20x4 air filters exist that are washable and reusable, but most are disposable and need to be replaced. Washable kinds of filters are made from electrostatic materials and can be rinsed and reused. They’re a cost-effective and eco-friendly choice, but have lower MERV ratings, so they might not capture as many fine particles as disposable filters do.
Thicker 20x20x4 filters have advantages over thinner options because of their ability to trap more dust, allergens, and airborne particles while also keeping airflow stable. Their longer life span means fewer replacements are needed, and ensures lower maintenance costs. Hospitals, manufacturing facilities, and business offices use 20x20x4 filters to trap contaminants that quickly accumulate. Thinner filters miss small particulates and clog up faster, restricting airflow, forcing the HVAC system to work harder. This may cause premature wear and tear on HVAC units. A 20x20x4 filter lasts 90 days or longer, but a thinner filter has to be replaced every 30 to 60 days.