Guide
MERV ratings explained
What the numbers on your filter mean and how to choose one that protects your family, not just your furnace.
Quick answer
MERV (Minimum Efficiency Reporting Value) rates how well a filter captures particles from 0.3 to 10 microns on a 1 to 16 scale. MERV 8 catches dust and pollen; MERV 11 adds pet dander; MERV 13 captures a large share of fine particles and bacteria; MERV 16 captures over 95% of particles down to 0.3 microns. Higher MERV needs more surface area to keep airflow up.
The MERV scale in practice
| Rating | Captures | Good for |
|---|---|---|
| MERV 1–4 | Lint, large dust | Protecting equipment only |
| MERV 8 | Dust, pollen, dust mite debris | Basic homes |
| MERV 11 | Adds pet dander and finer dust (Honeywell F100) | Homes with pets |
| MERV 13 | A large share of fine particles, smoke and bacteria (Honeywell F200) | Recommended minimum |
| MERV 16 | Over 95% of particles down to 0.3 microns (Lennox Carbon Clean 16) | Allergies, asthma, smoke |
| HEPA-grade | Finest capture with high surface area (NovusAer) | Maximum protection |
Four kinds of filter media
- Spun fiberglass: inexpensive and loosely woven; protects equipment from large debris but does little for air quality
- Pleated polyester or cotton blends: folds increase surface area to catch finer allergens and last longer
- Electrostatically charged synthetics: an electric charge pulls smoke and fine dust out of the airstream
- Activated carbon: adsorbs household odors, gases and chemical fumes
Why surface area matters
A denser filter catches smaller particles but resists airflow. Squeeze a high-MERV 1-inch filter into a slot built for a cheap one and your blower works harder while less air gets filtered. A 4- to 5-inch media cabinet, or a high-surface-area system like NovusAer, solves this by spreading the air across much more media.
Related
FAQ
Frequently asked questions
What MERV rating is best for a home?
MERV 13 is a strong minimum for most homes. MERV 16 or HEPA-grade is best for allergies, asthma, pets or wildfire smoke, as long as the filter cabinet has enough surface area for good airflow.
Is MERV 16 the same as HEPA?
No. They’re rated under different standards. MERV 16 captures over 95% of particles from 0.3 to 1 micron. HEPA-grade whole-home systems pair very fine media with much more surface area.
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