What does MERV 13 mean?
MERV is a rating of how well an air filter captures particles between 0.3 and 10 microns, on a scale from 1 to 16. MERV 13 is a higher-efficiency filter that the EPA suggests choosing, or higher, as long as your system can handle it.
Action level Worth checking
- Why you are seeing it
- It is printed on the packaging of a furnace or air conditioner filter, and sometimes in advice about improving the air indoors.
- Why it matters
- The number tells you how well the filter captures particles, so it is the quickest way to compare two filters. The EPA suggests MERV 13 or higher, as far as your system can accommodate.
- What should I do?
- Look at the rating and the size on the filter you use now.
- Check your system's manual or its maker for the highest rating it can accommodate.
- Buy the same size, at a rating your system can take.
- A common misunderstanding
- A higher number is not automatically the right choice for every system. The EPA's own advice is to choose as high as your system fan and filter slot can accommodate.
What the number measures
MERV stands for Minimum Efficiency Reporting Value. The rating reports how well a filter captures particles between 0.3 and 10 micrometers (µm) across. The scale shown by the EPA runs from 1 to 16, and the higher the number, the better the filter is at trapping specific sizes of particles.
What MERV 13 captures
| Particle size | Captured by a MERV 13 filter |
|---|---|
| 0.3 to 1.0 µm | At least 50% |
| 1.0 to 3.0 µm | At least 85% |
| 3.0 to 10.0 µm | At least 90% |
A simple example
Reading a package
A box says "MERV 13, 20 x 25 x 1".
MERV 13 is the efficiency rating; 20 x 25 x 1 is the size in inches. Both have to suit your system.
If your current filter says MERV 8, the box in your hand is a higher-efficiency filter, and the question to ask is whether your system can accommodate it.
What to check before you buy
- Your system: the EPA advice is to choose a filter with at least a MERV 13 rating, or as high a rating as your system fan and filter slot can accommodate. The fan and the slot decide what fits.
- The size printed on your current filter, because a filter has to fit the slot.
- The owner's manual or the maker of your system, if you are not sure what it can take.