MERV 8 is good filtration. MERV 11 is better, and MERV 13 might be called best filtration among these three. How well an air filter traps particles is an important consideration, of course, but there are other factors to think about when answering the question, What is the best MERV? MERV 8, 11 or 13 could all be the right MERV rating for your furnace or air handler depending on your circumstances.
All of those considerations are discussed below, and after reading this Pick HVAC guide to MERV 8 vs MERV 11 vs MERV 13 air filters, you’ll understand which one to choose.
But first, here’s a chart showing what MERV 8 vs 11 vs 13 air filters trap. Details are found below.
|Dust Mite Debris
|Up to 1200
|Up to 1200
Note: MPR is Microparticle Performance Rating, and it is 3M’s version of MERV. 3M applies it to its popular Filtrete air filters. FPR is Filter Performance Rating and is used by Home Depot on its branded air filters. There is much more information on air filter ratings and performance in our MERV vs MPR vs FPR Ratings guide.
If this Topic is New to You – An Introduction
MERV 8? 11? 13? Whatever!
Homeowners know that regularly changing your HVAC filter will help prevent dust, dirt and debris from clogging their HVAC system, preventing it from running smoothly and efficiently.
What many people don’t know is that not all HVAC filters are the same. Some filters are made to be dense and powerful to trap microscopic particles in the air, while other filters are designed to have a loosely woven design that only traps the bigger debris. HVAC filters are differentiated by their MERV rating. This page will compare MERV ratings 8, 11, and 13, and explain how to pick the right MERV rating for your home.
What is MERV Rating?
MERV stands for “Minimum Efficiency Reporting Value.” OK. Not helpful.
What you probably already know is that MERV rating is a measurement of how effectively the filter removes materials from the air flowing through it. It’s not just about the amount of the “stuff” the filter traps; it’s about the size of the particles they capture too.
MERV ratings range from 1 to 20 with 1 being the lowest filtering capacity and 20 being the highest filtering capacity.
Finding the Sweet Spot: Is a Higher MERV Rating Always Better?
No! You may think that because a higher MERV rating means more and smaller particles are removed from the airflow in your house, that a higher MERV rating is always better, but this is not the case! Why? Higher MERV is better for air quality, but might not be good for HVAC equipment including the blower motor and compressor – two key pieces of equipment that are expensive to replace.
Density and Airflow: Filters with high MERV ratings usually have denser fibers. That’s why they catch more and smaller particles.
But there is a potential downside. This dense filtering material makes it tougher for the air handler or furnace’s blower fan to pull air through the filter and into your home. Over time, this puts wear and tear on the blower, which shortens its life span and might cause it to fail and require replacing earlier than is normal. It gets worse!
When airflow is restricted, let’s say during an AC cycle, cooled air isn’t getting out of the system and to the thermostat, so the thermostat keeps the system working overtime. This can also cause the AC’s compressor, which is pumping refrigerant through the system, to overheat and fail. When your compressor fails, it’s generally time to replace the whole outside unit. All because the filter was too thick? Yes. It happens frequently, as any pro technician will tell you.
A filter with a MERV rating that is too high for your needs will also be less energy efficient because equipment must work harder:
- The fan whenever the system is running
- The burner when a furnace is running
- The compressor on an AC when cooling
- The compressor on a heat pump when heating and cooling
The key: Rather than getting a filter with the highest MERV rating you can find, your goal as a homeowner is to find the sweet spot for your home – Good filtration that doesn’t harm your HVAC equipment.
How to Pick the Best MERV Rating for Your Home
As a homeowner looking for the best filter for your HVAC system, the first step is to check your system’s documentation/owner’s manual. It should have information about the maximum MERV rating your system can handle.
In general, the highest MERV rating that is safe for residential use is MERV 13, although a rating that high is rarely needed in a residential home unless someone has severe dust allergies or asthma and needs advanced air filtering.
We recommend choosing a filter with a MERV rating between 8 and 13 for your HVAC system. A MERV rating higher than 13 will likely wear out or damage your equipment, and a MERV rating lower than 8 may not effectively remove particles from the air in your home.
Within the MERV 8 to 13 range, the best MERV rating for your home depends on a few factors. Here are three things to consider when choosing a MERV rating for your home’s HVAC filter:
1. What is your climate like? Do you live in an arid, desert-like area with lots of dust? If your climate produces a lot of dust particles in the air, you may want to consider an air filter with a higher MERV rating, like an 11 or 13.
2. What is your household’s health like? Does anyone in your home suffer from allergies, asthma, or other respiratory issues? If so, a filter with a higher MERV rating might be just right for you. Consider a MERV 11 or 13 filter to keep the air in your home pure and clean.
3. Do you have indoor pets? Your furry friends may be bringing a lot of dust and hair into your home, which can cause allergies to act up and lower the overall air quality inside the house. Getting an air filter with a higher MERV rating is a great way to keep your home comfortable for you and your four-legged household members.
If none of these factors are a concern for your household and there is no other reason why you need a higher level of filtration in your home, then a MERV 8 to MERV 10 filter is probably the best choice for you. Filters in this range will remove particles and keep your home’s airflow clean enough without overworking your HVAC system.
Comparing MERV Ratings 8 vs MERV 11 vs MERV 13
What is the difference between filters with these three common MERV ratings? Each filter traps pollutants and allergens of different types and sizes. Particle size is measured in a unit called “microns.” One micron is 1/1000 millimeter. The human eye can see particles that are about 25 microns in size, but not much smaller.
Below is a description of each MERV rating and the particles they trap.
Filters with a MERV 8 rating are the most common type in the United States. Why are they so popular? MERV 8 filters are budget-friendly and easy to find anywhere that sells filters. They are also effective at removing most airborne particles that could cause allergies or asthma to flare up without putting too much strain on the HVAC air blower or compressor.
What size particles do MERV 8 filters trap?
MERV 8 filters trap particles sized 3 to 10 microns.
How effective are MERV 8 filters?
MERV 8 filters are effective at trapping 90% of the airborne particles found in the average home.
How often do MERV 8 filters need to be changed?
Experts recommend that MERV 8 filters be changed every 2-3 months to keep them running at full capacity. How much you run your HVAC system should be considered. Your filter will get dirty faster, for example, in winter and summer because it runs more than in spring and fall. There’s more good information on this topic on this page of PickHVAC.
Which particles do MERV 8 filters trap?
MERV 8 filters trap dust, lint, debris, pet hair, small bugs such as dust mites, particles from sanding or spray painting, and textile fibers from clothes or carpet.
Where do MERV 8 filters work best?
MERV 8 filters work best in residential homes with average filtration needs.
MERV 11 filters are a great option if you need to take your filtration to the next level without restricting airflow too much. They remove an impressive amount of airborne materials including harmful microscopic particles. MERV 11 filters are often found in places that require enhanced air filtration, such as commercial buildings and senior living facilities. They are more expensive than MERV 8 filters, but they are still easy to find and won’t break the bank.
What size particles do MERV 11 filters trap?
MERV 11 filters trap particles sized 1 to 3 microns.
How effective are MERV 11 filters?
MERV 11 filters are effective at trapping 95% of airborne particles in a typical home.
How often do MERV 11 filters need to be changed?
Since MERV 11 filters have fibers that are denser than MERV 8 filters, they tend to fill up with trapped debris more quickly. The best practice is to change your MERV 11 filter every 1 to 3 months for maximum efficiency, again, depending on the season and how hard your HVAC equipment is working.
Which particles do MERV 11 filters trap?
In addition to everything that MERV 8 filters trap, MERV 11 filters trap mold spores, lead dust, welding fumes, car fumes, humidifier dust, and other machinery fumes and emissions.
Where do MERV 11 filters work best?
MERV 11 filters work best in residential homes with filtration needs than MERV 8 filters provide, commercial buildings, senior living facilities, and non-surgical hospital areas.
MERV 13 filters offer superior filtration of some of the smallest pollutants. While not used in residential homes as much, MERV 13 filters can be a great choice for commercial buildings or medical facilities that require next-level air purity.
What size particles do MERV 13 filters trap?
MERV 13 filters trap particles sized 0.3 to 1 micron.
How effective are MERV 13 filters?
MERV 13 filters are effective at trapping 98% of airborne particles found in an average home.
How often do MERV 13 filters need to be changed?
MERV 13 are the densest filter types discussed here, and so they need to be changed more regularly than types with lower MERV ratings. It is recommended that you change a MERV 13 filter every 1-2 months, especially when the furnace or air handler is running a lot.
Which particles do MERV 13 filters trap?
MERV 13 filters specialize in trapping tiny particles like airborne bacteria and smoke. In addition to everything that MERV 8 and MERV 11 filters trap, MERV 13 filters also trap tobacco smoke, smoke from fires, pollutants in bodily fluids released through sneezing and coughing, and bacteria.
Where do MERV 13 filters work best?
MERV 13 filters are rarely used in residential homes except in the case of someone with extreme filtration needs, such as an immunocompromised person or someone in home hospice care. MERV 13 filters are most commonly used in pharmacies, surgical facilities, and smoking lounges.
Action Steps for Choosing the Best MERV Rating
We’re looking for that sweet spot – good air filtration that won’t reduce airflow enough to make your equipment work too hard or lower its energy efficiency.
1. Know what MERV filter the manufacturer recommends. If you don’t have the manual, search the furnace or air handler model number online. Many manufacturer sites have a page, like this Lennox page, where you can put in the model number and get a .pdf of the manual.
2. Monitor energy costs. If you install a filter higher than the one you’ve been using, like if you upgrade from MERV 8 to MERV 11, watch your energy bills. Compare them to last year’s. Are you using more energy and getting higher utility bills? Is the slightly cleaner air worth the extra cost to you? If so, that’s the price paid for more breathable air. If not, go back to the lower-MERV filters.
3. How comfortable is your home? If you start using a higher MERV filter, like going from a MERV 11 to MERV 13, do you notice reduced airflow through the vents? Are rooms distant from the furnace or air handler cooler in winter and warmer in summer – meaning they’re not getting enough heat or AC? If so, the filter is too dense, and you should consider going back to the less-dense filter.
4. Do people feel worse? If you reduce the MERV rating, from 13 to 11 or 11 to 8 for example, take notice whether allergies or asthma gets worse. Is your home dustier? These are indicators you should try a higher MERV filter – while keeping an eye on energy costs and the comfort of your home. Another option is to use a MERV 8 or 11 filter and add an air purifier to your home designed to remove allergy-causing impurities.
When you balance all these issues, you will indeed find the sweet spot on the MERV 8 vs MERV 11 vs MERV 13 spectrum.