Buying the best air filter for your HVAC system can be challenging. It's not as simple as choosing the filter that removes the most particles and airborne pollutants. Air filtration is always a balance between cost, filtering efficiency, and the needs and capabilities of your HVAC equipment.
The Minimum Efficiency Reporting Value (MERV) is a rating intended to help consumers understand how effective a particular HVAC air filter is, but a higher MERV rating can affect more than just filtration efficiency. It has implications for filter cost, HVAC system airflow, replacement frequency, and other factors.
This article explores how the MERV rating works and compares air filters with two common MERV ratings—MERV 11 and MERV 13.
What Does the MERV Rating Mean?
Air filters are made of fibrous materials like paper, fiberglass, or meshes designed to let air through while trapping particles. The size of the openings in the filter medium is one of the factors that dictates the particle size it can capture. MERV ratings measure how effective air filters are at capturing airborne particles between 0.3 and 10 microns in size.
When discussing MERV ratings, it's helpful to understand how big the particles you might want to filter are. Here's a table of typical micron particle sizes for commonly encountered airborne pollutants. It’s worth noting that particles vary in size, even within categories, so the table should be taken as a rough guide.
Size in Microns
Beach Sand (for scale)
100 and larger
0.5 to 100
3 to 40
2.5 to 200
Less than 2.5 to 10
0.3 to 8
0.2 to 3
0.1 to 0.5
0.005 to 0.3
MERV ratings are numbered 1 to 20. A higher rating means the filter can trap smaller particles more efficiently, enhancing indoor air quality by removing more contaminants.
MERV 11 Explained
A MERV 11 filter captures at least 85% of particles in the 3-10 micron range and at least 65% in the 1-3 micron range, such as pet dander, dust mite debris, and pollen. It also captures over 20% of particles in the 0.3 to 1 micron range, including bacteria and wood smoke.
MERV 13 Explained
MERV 13 filters offer an even higher level of air purification, capturing more than 50% of fine particles in the 0.3–1.0 micron range, over 85% of 1–3 micron particles, and over 90% of 3-10 micron particles.
That makes MERV 13 filters highly effective for improving indoor air quality, particularly in environments where air cleanliness is crucial, such as homes with allergy sufferers, hospitals, and other healthcare settings.
MERV Ratings and Static Pressure
Air filters with higher MERV ratings prevent smaller particles from getting through, but they also can make it more difficult for air to circulate depending on how the filter is engineered. In general, the higher the MERV rating, the harder your HVAC system has to work to circulate the same amount of air. Or, to put it another way, if your HVAC system's blowers are insufficiently powerful, less air will be filtered overall.
In the HVAC industry, this resistance to airflow is called static pressure. A filter’s MERV rating isn’t the only factor affecting static pressure—the type and size of air filters also play a role—but it should be considered when choosing between MERV 11 and MERV 13 filters. Looks for brands that have lower static pressure which is usually stated as initial resistance.
Choosing The Right MERV Rating for Your HVAC System
Now you understand what MERV 11 and MERV 13 mean, let's look at some questions that will help you make the best decision for your circumstances.
What Does Your Equipment Manufacturer Recommend?
Your HVAC equipment's manufacturer designed the system with a specific range of static pressures in mind. Installing an air filter that exceeds the system's capabilities will reduce its effectiveness and efficiency and could shorten the lifespan of its components.
Check the manual or the manufacturer's website and, if in doubt, consult with a qualified HVAC engineer.
Do You Have Specific Air Quality Concerns or Allergen Sensitivities?
If you live in a high-pollution area, have pets, or are sensitive to allergens that standard domestic MERV 8 filters cannot sufficiently remove, a MERV 11 filter can be an excellent choice.
MERV 13 filters are commonly used in commercial, industrial, and some healthcare settings, but they are also used in residences with people who have health conditions that require very clean air, such as allergies, respiratory conditions, or weakened immune systems.
Learn more with our MERV 8 vs MERV 11 comparison!
What Is Your Budget?
You should know the cost implications when choosing a higher MERV-rated air filter. Higher-rated filters tend to be more expensive because they are more difficult to manufacture. Additionally, you may need to clean or replace higher-rated filters more often if you live in an area that has a high particulate environment such as the desert or have frequent fires, because they capture more particles and can become loaded more quickly.
Is MERV 13 Too High?
The most commonly used air filters in typical domestic environments have a rating of MERV 8. They are inexpensive and capable of capturing most indoor particles.
However, whether MERV 13 is "too high" depends on your needs and HVAC equipment. MERV 11 and MERV 13 air filters are ideal for people who desire or require more thorough air filtration and have a suitable HVAC system.
MERV 11 and MERV 13 Air Filters at Atomic Filters
Atomic Filters carries a comprehensive range of MERV 11 and MERV 13 Filters from leading manufacturers. Our MERV 11 Air Filters provide outstanding filtration at cost-effective prices. Consider our Ultra Premium MERV 13 air filters if you need more comprehensive air filtration.
Our air filters are available in 1", 2", and 4" thicknesses as well as specialized sizes for common systems for Carrier, Lennox, Honeywell, Trane, TopTech and many more. Atomic makes it easy to see what your MERV rating is on our filters by the color of the filter media. Green media is MERV 13, Blue Media is MERV 11 and White media is MERV 8.