Are you curious as to how the MERV filter rating compares to the MPR scale?
Comparing MERV and MPR is important in choosing the right filter quality for your HVAC system because too high of a rating may harm your HVAC, and too low may create air quality issues.
In this guide, I will go over...
- How MERV is different than MPR
- A quick summary on both systems
- An equivalency table for MERV & MPR
- My slight preference for 3M's MPR rating system
Let's get started with this guide!
MERV Vs. MPR — How Do They Compare?
In the home products industry, there are a lot of acronyms floating around such as R-value, CFM, and perhaps the most important — MERV and MPR. Here is the lowdown on exactly how they compare...
The biggest difference between MERV and MPR is that MPR only measures microparticles which is in the 0.3 to 1 micron size range. MERV measures microparticles also, but only in filters rated at MERV 11 or higher. Another important distinction is that MERV is an industry wide filter rating standard, whereas MPR is only used for 3M's line of Filtrete HVAC filters.
MERV stands for minimum efficiency reporting value and is the industry standard for HVAC filter ratings. In ranges from 1-16, with the low end being lower quality filters, and the upper ranges verging on hospital levels of HVAC filtration. MPR ratings range from a low of 100 (equivalent to MERV 1) and as high as MPR 2800 (equivalent to MERV 14).
MERV Vs. MPR Equivalency Table
What Is The MERV Filter Rating?
MERV stands for minimum efficiency reporting value, and it is an HVAC industry standard for filter ratings.
MERV was developed by ASHRAE (American Society of Heating, Refrigerating, & Air-Conditioning Engineers) in 1987 and has since then been adopted by many organizations and governments as a filtration standard.
The MERV filter rating measures the amount of microparticles and macroparticles in the air — from 0.3 microns and 10 microns in size. For comparison, a grain of sand is about 60 microns.
When a particle is in the 0.3 to 1 micron in size it is considered microparticle. With the MERV system, microparticles are not measured on the MERV scale until until it reaches MERV 11.
Read Also: What Are The Best AC Filters For Allergies?
MERV Laboratory Testing
This filter rating system was developed by sending a aerosolized spray of test particles of uniform size through a filter and measuring the upstream and downstream particle quantity. And after they do this air stream for six test cycles, and they take the worst peformance reading and then assign it a MERV value.
They don't want to fall into the trap of averages which is why they take the least performing value.
Particle counts are taken over the range of particle sizes six times, beginning with a clean filter and then after the addition of standard synthetic ASHRAE dust loadings for five additional measurement cycles.
MERV 1 Through MERV 4
MERV 1-4 is for the lowest performing filters. These are the low quality fiberglass filters that some people purchase, and which makes home inspectors like me crazy.
These low performing filters will only filter out things like carpet fibers, dust mites, dust particles, and some pollen.
MERV 5 Through MERV 8
MERV 5-8 is representative of average HVAC filters. Personally, I recommend buying a furnace filter with at minimum a MERV 8 rating. This will give you optimal filtration but without a large pressure drop (reduced air flow) on your HVAC system.
MERV 9 Through MERV 12
When you reach the 9-12 MERV range, this is consider superior residential air filtration.
I would only recommend going for a 9-12 filter under special circumstances such as if someone in your household suffers from allergies.
You may also want to consider the 9-12 range if you live in a highly polluted area of the country where there may be smog or low air quality from time to time. Also, if you live in a dusty arid region, where dust storms may be common — should also consider a 9-12 filter. Here is my guide on the best HVAC filters for dust control if you live in one of these areas.
If you have pets, and shedding is a problem, a higher MERV filter may also be warranted.
Read Also: What Are The Best Furnace Filters For Odors?
What Is The MPR Filter Rating?
The MPR hvac filter rating system was created by 3M and is used with their Filtrete line of filter products.
MPR stands for microparticle performance rating and it measures microparticles which are considered to be in the range of 0.3 to 1 micron. For comparison, a human blood cell is about 5 microns in diameter.
Filtrete filters have MPR ratings from as low as 100 (equivalent to MERV 1) and they go as high as MPR 2800 (equivelent to MERV 14). So the higher the MPR rating, the more microparticle types your filter will catch.
At the higher MPR ratings, they can even catch bacteria and viruses — hospital quality of filtration. But again, you have to factor in that there will be a pressure drop associated with higher MERV filters, and you have to be careful as to how high of a rating you go.
Their highest filter, the Healthy Living MPR 2800 by Filtrete, is on a level of hospital or surgery level of air filtration — and it is equivalent to MERV 14.
One nice aspect of the MPR rating (and their filters) is that 3M factors in air resistance into their filters and the rating scale. 3M has designed their filters so that there is less of an initial HVAC pressure drop as well as over the life of the filter.
And as stated earlier, microparticles are only measured (0.3 to 1 micron) on the MERV scale when it reaches at least 11.
Final Thoughts: Is MPR Better Than MERV?
Even though it is nice that MERV is an industry standard, this doesn't guarantee uniform quality across all air filters. Some air filters may produce a significant pressure drop on your HVAC system while the same MERV filter of a different brand does not.
I would only regard MERV as a rough equivalency among filters, and it isn't something to be taken as gospel because of other considerations.
And the biggest difference between MPR and MERV is that MPR is only for rating the level of microparticle filtration — in the range of 0.3 to 1 micron in size. For MERV ratings, microparticles are only even measured when it reaches MERV 11 or higher.
And for most residential HVAC systems, MERV 11 is already overkill and not needed.
In my opinion, if microparticles are a big concern for you because of allergies, pets, or outdoor air pollution — I think the MPR rating system (as well as the Filtrete line of filters) is a better choice. I recently wrote a guide on the best filters for allergies with these higher MERV ratings to capture more pollen, dust, and pet dander.