Understanding Air Filter Ratings: HEPA, MERV, and FPR

The air quality in our homes is important to us, but we often take the air for granted. The air that we breathe has a direct impact on our health and well-being. If you are looking for an easy way to improve your indoor air quality, then installing an HVAC system with a high-efficiency particulate air (HEPA) filter may be just what you need! Air filters do not all have the same ratings though, so it can be difficult to know which one will work best for your needs.

The most common ratings are HEPA, MERV, and FPR. If you are searching for a replacement air filter online, it is important to know terms like "HEPA" - and if you see a product labeled, for example, "MERV 8" or "FPR 4" - you'll want to have an understanding of what it means! In this article, we will break down how different types of filters are rated and help you decide which type is right for you and your family.

hepa air filter rating

What determines an air filter rating?

The rating of an air filter is determined by how well it captures and traps dust, pollen, and other particles from the air. It also matters what size particles the filter can capture. In the micro world, airborne particles come in a variety of different forms and sizes, and oftentimes it is the smallest particles that are the most dangerous.

There is a measurable level in which we call an air particle "small" or "large": A particle is considered "large" if it is greater than or equal to 0.0625 millimeters in diameter, and below that number, it is considered a small or "fine" particle. However, not all filters can capture fine particles! So, which one can?

HEPA Filters

HEPA filters are the most common type of air filter and arguably one of the most efficient air cleaners; it is considered the "gold standard" of air filtration. They can capture both large and small (or fine) particles; HEPA filters get their rating by the size of the particles they can capture.

A HEPA filter will capture 99.97% of all particles as small as 0.03 microns. That is twice as small as what is considered a "large" particle. In fact, particles of this size are about 30% smaller than the diameter of human hair! It's no wonder HEPA filters are so efficient at relieving allergy and asthma symptoms.

What does a "HEPA" rating mean?

Unlike MERV and FPR, HEPA filters aren't rated on a numeric scale. Filters that qualify as HEPA will technically have a MERV rating of 12 or higher, which means they are effective at removing 99.97% of particles from the air.

allergies asthma air filters

HEPA filters are most suitable for those with allergies or asthma, as they remove the majority of dust and pollen particles from indoor air. They are used in air filtration systems for hospitals, clean rooms in manufacturing facilities, and are commonly used in homes with allergy sufferers, smokers, and pets.

What is a MERV-rated filter?

The Minimum Efficiency Reporting Value, or MERV rating, is a number between one and sixteen that represents the efficiency of an air filter at removing particles from indoor air. The higher the number, the more efficient it is at capturing small particles.

MERV 12-16

A highly efficient MERV filter will be rated anywhere between 12 and 16. For reference, filters with a MERV rating of twelve are about 95% effective at removing particles from the air and those with a MERV rating of thirteen are about 98% effective.

MERV 8-11

Most residential air filters have a MERV rating of eight or higher. A MERV rating of eight to eleven is still considered "high efficiency" and can remove up to 85% of air particles. These types of filters are best suited for people with moderate allergies or asthma who want cleaner indoor air but do not necessarily need an air filter that removes all allergens from the environment.

MERV 1-7

Filters with a MERV rating of one to seven are considered "medium efficiency" and they remove fewer air particles from the environment. These types of filters can be used in homes that do not have allergy sufferers or pets; however, most homeowners will opt for an air filter with a higher MERV rating because it is more efficient at removing smaller particles. If you are looking for an inexpensive air filter and do not have asthma sufferers in your home, this filter is a good option.

What is an FPR-rated filter?

FPR, or "filtration performance rating," measures air filter performance by its ability to capture both large and small particles, as well as its pressure drop as it is used over time. “Pressure drop” simply refers to the resistance caused by the filter as it captures small particles.

FPR ratings range from four to ten, with ten being the highest and most efficient. These types of filters are often used in hospitals and other large facilities where clean air is critical.

An FPR four or five filter is considered the least effective filter that can capture large but not fine particles; they may be used in areas where regular cleaning is possible because their performance degrades significantly over time due to dust accumulation or clogging.

Whereas, an FPR six or higher can trap up to 85% of airborne particulates in a typical home.

air filter replacement

An FPR rating will give you a better idea of how well your air filter will work over time; however, it is important to remember that even the most efficient air filters will lose their ability to trap particles as they age and accumulate dirt. Every filter must be replaced eventually.

An FPR four filter typically lasts about six months, whereas an FPR six or higher can last anywhere from one to three years depending on how contaminated your air is.


There are a variety of air filters on the market and it can be confusing to know which one is right for you. Each filter offers unique benefits depending on your specific needs for indoor air quality improvement. The best way to figure out which filter is right for your home is by understanding how they are rated.

HEPA filters are the most efficient at removing allergens from indoor air, followed by MERV 12-16 filters. Most residential air filters have a MERV rating of eight or higher, so these should be suitable for people with moderate allergies or asthma. FPR ratings range from four to ten, with six being the most common and effective rating.

With the insight into how these different scales work, you can make an informed decision about the air filter that will work best for you. All different types of air filters can be found at the LifeSupplyUSA store. Most of them are HEPA-rated filters and will perform brilliantly, but a variety of MERV-rated filters can be found as well – all at affordable prices!

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