What Is A True HEPA Filter? – And What Makes Them Different Than HEPA Filters?

Planning to get an air purifier? You might have been researching the best air purifier for home use, right?

And during your research, you might have stumbled upon some terms. Although most of the jargon is easy to understand, the term True HEPA Filter can throw you off.

So, what is a true HEPA filter?

True HEPA filters conform closest to the DOE standard of HEPA air filters. At its maximum efficiency, it can clear out 99.97 % of all particles that are 0.3-micron in size. Some can even filter out particles that are smaller than that.

But isn’t the efficiency the same for all HEPA filters? If not, what makes the other HEPA filters stand out? Let’s answer them all for you!

Understanding the HEPA Standard

To understand the True HEPA filter, you must first have a fair idea about the HEPA standard. The full form of HEPA is “High-Efficiency Particulate Air.”

Generally, a HEPA filter is utilized by a mat of dense fibers that will trap particulates as they move through.

But how does a mat of dense fibers gain the HEPA standard?

Well, it must be able to capture 99.97 percent of air particulates that are 0.3 microns.

So, you can say that HEPA filters are highly effective in capturing small particulates.

However, it does not mean HEPA filters can not capture particles smaller than 0.3 microns. They can, but the effectiveness decreases as the particles get smaller.

You should also note that the HEPA standard in Europe is a bit different.

But not many brands utilize Europe standards, which is the reason why we will stick with the US standard throughout the rest of this discussion.

True HEPA Vs. HEPA Filter – What Is the Difference

So, to gain the HEPA filter, the mat of dense fibers must have 99.97 percent efficiency in capturing particles that are 0.3 microns in size. But what makes one get the “True” prefix while the other has no prefix at all?

An overview of the factors on the difference will give you a full and clear picture of what makes a ‘True HEPA’ stand out from ‘Regular HEPA’ filters.

True HEPA Filters Strictly Conform to the DOE Standard

Unlike regular HEPA filters, the true HEPA filters will truly stick with the DOE standard of HEPA filtration units. On the other hand, traditional HEPA filters do not conform with the DOE standards but not as closely as True HEPA filters.

True HEPA Filters Are More Effective

As the True HEPA filters truly conform with the DOE standards, they hit the 99.97 percent threshold. In other words, True HEPA filters have higher overall efficiency.

True HEPA filters Go Through Many Third-Party Testing

Any company can claim that they are utilizing True HEPA filters. However, without any third-party testing, they are just regular HEPA filters. Generally, products with True HEPA filters will let you source all the third-party testing information.

All that information will tell you that the brand has followed all the proper steps. It will also inform you that the filter unit adheres to the DOE standards.

True HEPA Filters Go Through Efficiency Tests

Lastly, True HEPA filters must undergo efficiency tests before getting the “True” prefix. Again, the filters are nothing but a regular HEPA filter unit if they do not go through the efficiency tests.

Are True HEPA Filters Safe?

The True HEPA filters undergo a lot of testing and screening before being put into an air purification device. Through those tests, the manufacturer ensures that the filtration unit conforms with all of the standards of the DOE (Dept. Of Energy).

According to the standards, the filter must have a 99.97 percent efficiency for capturing particles that are 0.3 microns in size.

So, considering that, you could safely say that True HEPA filters are 100 percent safe.

Furthermore, the True HEPA filters have gone through many studies and testing.

The researchers did not find any evidence of harm in the True HEPA filters from those tests. Therefore, you can rely on the True HEPA filters without any questions.

What MERV Rating Is a True HEPA Filter?

According to the MERV rating, all the HEPA filters must have a rating of 17 or higher.

To put that into perspective, a filter with a MERV rating of 17 will be capable of capturing 99.97 percent of air particles that are 0.3 microns to 10 microns in size.

Now, as the MERV rating for a regular HEPA filter needs to be 17, the True HEPA filters will have a higher rating than 17.

But the real question is, what does the MERV rating actually mean?

Well, the full form of MERV is Minimum Efficiency Report Values. It basically reports a filter’s ability to capture particles between 0.3 and 10 microns.

However, for a filter to get a high rating, it needs better overall efficiency in capturing particles that float around in the air.

What Is a HEPA-Type Filter? How Does It Differ from True HEPA Filter?

Due to all of the complications that HEPA filters need to go through during the manufacturing process, they are pretty costly.

So, the air filter market came up with a cheap but slightly inferior version of True HEPA, a HEPA-type filter.

As the name suggests, this filter is kind of similar to HEPA. The place where it first lags behind is in terms of efficiency.

Whereas the True HEPA filters have a 99.97 efficiency, HEPA-type holds 99 percent.

Secondly, and most importantly, the HEPA-type’s efficiency is for particles that are 0.2 microns in size.

Although the difference of 0.1 microns can make the HEPA-type filters look effective, it actually is not.

You see, in the air filter world, 0.3-micron particles are the most challenging particles to capture.

Through the True HEPA filter, the 0.3- micron particles will bounce into 0.1 microns particles.

In a nutshell, the True HEPA filters are more effective at capturing the particles that are challenging.

On the other hand, HEPA-type filters are not capable of handling the particles that are challenging for an air filter.

Other HEPA Jargon that You Should Know About

Apart from True HEPA and HEPA -like, there are other terms in the HEPA dictionary.

You should know about them if you want to pick the right air purifier for your home.


This filter is a variation of the HEPA-type filter. This is less common than the HEPA-type filter.

Nonetheless, the term is more like a marketing term. And you should not think that these filters closely conform to the standard of HEPA.


A couple of the brands will utilize this term to show off what their HEPA filter is capable of doing.

Basically, those air purifiers will claim that they are X times more effective than HEAP filters.

And they will also state that the filters can capture particles that are up to 0.003 microns in size.

Although that is technically possible, those filters are not fit for a consumer-grade product.

Permanent HEPA

Another marketing term for HEPA filters is Permanent HEPA.

As the name suggests, these filters are permanent, meaning that you will have to replace them as frequently as other HEPA filters.

Instead, you can wash them and reuse them in your air purifier device.

Absolute HEPA

This term is pretty much the same as True HEPA. However, some of the manufacturers will claim to offer higher overall efficiency than True HEPA with Absolute HEPA.

Frequently Asked Questions

1. Is HEPA 13 the same as true HEPA?

HEPA 13 has the ability to capture particles that are 0.2 microns in diameter with 99.95 percent efficiency. Considering that, you could say that the HEPA 13 and True HEPA are not the same things.

2. Is a true HEPA filter good?

True HEPA filters are excellent for filtering the air. They have a 99.97 percent efficiency in removing particles that are 0.3 microns in size.

3. How long does a true HEPA filter last?

Although true HEPA filters are great at filtering the air, they do not last forever. According to manufacturers, you need to replace True HEPA filters every 10 years.

Read More: What Is A Pre-Filter In An Air Purifier?

Final Words

So, what is a true HEPA filter? In short, it is the HEPA filter that is in line with the DOE standard HEPA.

It has an efficiency of 99.97 percent in terms of capturing particles that are 0.3 microns in size.

And as you can see, there are many other HEPA filters other than True HEPA. Check the standards before making a purchase.

Last Updated on February 9, 2023

Richard Hicks

Hello there! I hope you are enjoying your stay at my well-curated website. And I certainly am pleased to have you here. I hope that you got what got you here in the first place because that is the only thing that matters to my team and me. But that is not the end; there will be more content, such as the one that got you here.

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