MPR vs MERV: Which Furnace Filter Number Should You Trust?
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MERV is the rating that appears across brands, which makes it the one that supports comparison. MPR is a manufacturer's own scale printed alongside it. In our catalog the two Filtrete filters give two data points: MPR 1000 corresponds to MERV 11, and MPR 1900 corresponds to MERV 13. The Aerostar filter carries MERV 13 with no MPR at all, which is the practical reason to shop on MERV.
MERV, because it appears on filters from every brand and MPR appears on one. In our catalog the two Filtrete filters pair MPR 1000 with MERV 11 and MPR 1900 with MERV 13, while the Aerostar carries MERV 13 and no MPR at all. Only one of those numbers lets you compare the two MERV 13 filters against each other.
Those are two paired data points, not a conversion table.
Stand in front of the filter shelf and you are looking at packaging carrying numbers in the hundreds and thousands next to numbers in the low double digits. They are not measuring different amounts of the same thing. They are different scales, and one of them is only usable within a single brand.
What each number is for
MERV is the figure that shows up across manufacturers, which is the entire reason it is useful. When the EPA advises that a furnace or HVAC filter should be rated at least MERV 13, or as high as the system will accommodate, it can give that guidance precisely because MERV means the same thing on every box.
MPR is Filtrete's own scale, printed on Filtrete packaging. It is not wrong and it is not hidden — it sits alongside the MERV figure — but a number that exists on one brand's boxes cannot rank that brand against another.
The two data points we can actually show you
| Product | MERV | MPR | Nominal size | Pack count | Link |
|---|---|---|---|---|---|
| Filtrete Filtrete 12x24x1 Air Filter, MERV 11, MPR 1000 | 11 | 1000 | 12x24x1 | 4 | Check price |
| Filtrete Filtrete 20x25x1 Air Filter, MERV 13, MPR 1900 | 13 | 1900 | 20x25x1 | 2 | Check price |
| Aerostar Aerostar 20x25x1 Air Filter, MERV 13 | 13 | — | 20x25x1 | 6 | Check price |
- Filtrete 12x24x1 — MPR 1000, MERV 11.
- Filtrete 20x25x1 — MPR 1900, MERV 13.
- Aerostar 20x25x1 — MERV 13, no MPR published.
The comparison MPR cannot make
Look at the table again. The Filtrete 20x25x1 and the Aerostar 20x25x1 are both MERV 13 in the same nominal size. That is a real, like-for-like comparison, and it is available only because both filters publish MERV. There is no MPR figure on the Aerostar to compare against the Filtrete's 1900, so on that scale the two filters simply cannot be ranked.
Once you are comparing two MERV 13 filters in the same size, the differences that remain are physical: actual dimensions, and how many filters are in the pack.
MERV 13 with both ratings printed
Filtrete Filtrete 20x25x1 Air Filter, MERV 13, MPR 1900
Carries MPR 1900 and MERV 13 together, and states a three-month replacement interval. Sold in a two-pack, so it covers about six months at that interval.
- Merv Rating
- 13
- Mpr
- 1900
- Nominal Size
- 20x25x1
- Replace Months
- 3
- Pack Count
- 2
The same MERV 13, in a larger pack
Aerostar Aerostar 20x25x1 Air Filter, MERV 13
MERV 13 in the same nominal 20x25x1 size with no proprietary rating attached. The six-pack is the meaningful difference between this and the Filtrete above.
- Merv Rating
- 13
- Nominal Size
- 20x25x1
- Pack Count
- 6
- Pleated
- true
MERV 11, in a less common size
Filtrete Filtrete 12x24x1 Air Filter, MERV 11, MPR 1000
MPR 1000 and MERV 11 in 12x24x1. A step below MERV 13, which is a reasonable trade in a system that cannot take the higher restriction.
- Merv Rating
- 11
- Mpr
- 1000
- Nominal Size
- 12x24x1
- Replace Months
- 3
- Pack Count
- 4
We do not hold the test method or particle-size bands behind the MPR scale, and we have no MPR value for the Aerostar filter because none is published. Anything we said about how MPR behaves outside our two paired data points would be invention.
How to use this on the shelf
A short procedure that avoids the whole problem.
Find the MERV number and ignore everything larger
It is the only figure that will also be on the competing filter.
What to look for: The figure labelled MERV, usually printed smaller than the proprietary one.
Check what your system will take
The EPA's guidance is MERV 13 or as high as the system will accommodate, and the second clause is a real constraint on a one-inch filter.
What to look for: Symptoms of over-restriction: weak airflow at the registers, or an evaporator coil that freezes. We cover this in detail separately.
Match the nominal size exactly
Nominal size is what the slot is named; actual size is what the filter measures, and the two are never the same.
What to look for: The nominal figure printed on your old filter's frame, not a tape measure reading.
Then compare pack count
Once MERV and size match, this is one of the few remaining real differences.
What to look for: How many months of coverage the pack represents at the manufacturer's stated interval.
On that second criterion — whether your system can actually take MERV 13 — we go through the symptoms and the reasoning in what MERV rating your furnace can handle.
The short version
- MERV appears on filters from multiple brands; MPR does not.
- In our catalog: MPR 1000 is MERV 11, MPR 1900 is MERV 13.
- A high MPR number next to a modest MERV number is a scale difference, not a performance difference.
- The EPA's guidance is framed in MERV, which is another reason to shop on it.
Sources
- Dehumidifiers — ENERGY STAR
That dehumidifier capacity is measured in pints per 24 hours, and that the capacity needed depends on the size of the space and the conditions in it.
- Energy Conservation Program: Test Procedure for Dehumidifiers — US Department of Energy (Federal Register)
That a dehumidifier's capacity is defined by federal test procedure as the volume of water in pints removed from ambient air per day, normalized to a standard ambient temperature and relative humidity.
- A Brief Guide to Mold, Moisture and Your Home — US Environmental Protection Agency
That indoor humidity should be kept below 60 percent, ideally between 30 and 50 percent relative humidity.
- Guide to Air Cleaners in the Home — US Environmental Protection Agency
That a portable air cleaner should have a clean air delivery rate (CADR) large enough for the size of the room, that a higher CADR filters more particles and serves a larger area, and that most portable air cleaners carry a CADR rating on an AHAM label.
- Guide to Air Cleaners in the Home (room sizing) — US Environmental Protection Agency
That the room area should be compared against the maximum recommended room size on the packaging; that an open floor plan means considering the entire space the cleaner would serve; and that ceilings above 8 feet mean sizing up.
- Guide to Air Cleaners in the Home (furnace filters) — US Environmental Protection Agency
That a furnace or HVAC filter should be rated at least MERV 13, or as high as the system will accommodate, and that a dirty or overloaded filter does not work well.
- Air Changes per Hour FAQ — AHAM Verifide
That the AHAM Verifide seal gives a suggested room size based on 4.8 air changes per hour, alongside reduction rates for tobacco smoke, dust and pollen known as clean air delivery rates (CADR), and that certified units are independently tested by a third-party laboratory.
- Air Filtration Standards — AHAM Verifide
That AHAM's standard for measuring an air cleaner's efficacy is the Clean Air Delivery Rate (CADR), which indicates the volume of filtered air delivered with separate scores for tobacco smoke, pollen and dust, and that a higher CADR means faster filtering.