HEPA Type VS True HEPA Filters Explained

Air purifiers are wonderful and can definitely improve your quality of life. They have for me But products sold today on the market aren’t always easy to figure out. Air purifiers may be labeled “true” HEPA filters or “HEPA type.”

To make matters worse, as a new buyer it’s easy to be mislead into buying a product that is misrepresented and pretends to be just as good as the best purifiers.

We’ll compare HEPA type vs HEPA filters in great detail and explain the differences. I’d love to clear this up for you once and for all. The last thing I want you to do is end up with the wrong product and still suffer from air quality problems!

True HEPA and HEPA type air purifiers

HEPA type vs true HEPA purifier examples image

Shown: 2 very common air purifiers, which don’t appear very different from the outside. Left: A Holmes HAP242-NUC air purifier which includes a HEPA-type filter and marketed similarly to a true HEPA filter. Right: GermGuardian AC4825 air purifier. It includes a HEPA filter which meets the High Efficiency Particulate Air (HEPA) standard.

The problem with air purifiers sold today (as pictured above, for example) is that it’s very easy to think they’re all the same. Because of clever marketing you may think a HEPA-type is just as effective as a true HEPA product.

The problem lies in the details and how filters are rated.

What is a true HEPA filter?

Diagram showing HEPA filter efficiency
High Efficiency Particulate Air (HEPA) filter describes a type of filter designed to meet efficiency and air purification quality levels set by the United States Department of Energy. These filters are made of a very dense fiber-like material.

To meet the standard a filter must be able to remove 99.97% of airborne particles that enter it down to 0.3 microns in size. A micron, or micrometer, is 1/1,000,000 of a meter.

The efficiency refers how many particles it can trap and remove from a purifier’s airflow that enters it. At 99.97%, for every 10,000 particles flowing into it only about 3 escape.

They’re very effective at cleaning air.

The good news is that because the High Efficiency Particulate Air (HEPA) standard exists if you’re careful when selecting a product you can be absolutely sure of its performance.

HEPA-type vs. true HEPA explained

HEPA filter efficiency graph

This graph shows how typical air purifiers like HEPA filters perform.

A HEPA filter’s efficiency actually begins to fall for particles near the size of 0.3uM, which is why they’re rated to “99.97% of particles down to 0.3uM.” Filters actually work even better above that size (as seen in the graph, like 5uM for example).

Following the red line on the graph you can see that the efficiency (the amount of particles it can capture) drops a bit near a certain size range.

The interesting thing to know is that filters actually trap more particles below that size range, but it’s misleading to sell a filter based on that. The minimum particle size it works well at is the most important thing to know. In the case of a genuine (true) HEPA filter you can be sure that’s 0.3uM.

HEPA-type filters are those that look similar to true HEPA filters but don’t meet the same requirements. They are not standardized and can have any range of efficiency and minimum particle size cleaning.

HEPA-type purifiers are sold to give buyer the impression they’re getting the same performance when in fact who knows? Unless its specifically made clear, it’s anybody’s guess. There’s no requirement for companies selling those to have demonstrated performance.

HEPA-type marketing to watch out for

HEPA type filter marketing gimmic

You might find products advertised as having “99.9% efficiency” or something like that. But the most important thing is what’s the minimum particle size they can filter at that level? What is it? How does it really perform?

Unless it’s specifically made clear, you have no idea how well it’s actually going to perform. More than likely it’s not close to the performance of a true HEPA filter and is a bad choice.

In some cases HEPA-type filters can allow allergens, dust mite particles, and more to escape! That’s because some of the most common airborne particles that give people problems are smaller than they can capture.

HEPA type vs true HEPA visual comparison image

Image showing the filters from the previously shown examples. A HEPA-type filter (Holmes air purifier, left) and a true HEPA filter (GermGuardian, right) look extremely similar. In most cases you won’t be able to visually tell the differences. You’ll need to be very careful and look for specifications that tell you their performance. However in my opinion “HEPA-type” filters are best avoided and you should simply get the real thing.

Avoid unknown HEPA-type filters. Don’t waste your money.

Are HEPA type purifiers bad? Are there exceptions?

Holmes HAP242-NUC hepa type description

As I mentioned earlier, it’s generally best to avoid HEPA-type purifiers. But there are exceptions to the rule.

The Holmes desktop air purifier I showed earlier is an example I can use. It’s it’s more of a budget model. However, in this case, Holmes does specify it can trap contaminants down to 2 microns (2uM) in size.

While that’s poor in comparison to a real HEPA filter, it’s still ok for some purposes. For example, for larger particles like dust mites, household dust, hair, and so forth it can work.

In that case you’ll have to be well-informed about what size particles your air problems include. I definitely wouldn’t recommend a HEPA-type filter for smoke, airborne microbes, and other issues. Smoke particles have been shown to fall to well below 1 micron in size.

Honestly, this kind of information is not for the average person and leaves too much room for making a bad buying decision in my opinion.

If you’re on a tight budget and your air problems aren’t more demanding they are a possibility to consider.

However, a better purifier with a real HEPA and carbon filter can be bought for around $50 these days.


As they look very similar to each other, you can’t rely on your eyes alone. And as I mentioned earlier, because of clever marketing you may be mislead to think HEPA-type purifiers are just as good as the real thing. When in fact they aren’t!

To recap, here are the most critical points to keep in mind when comparing HEPA type vs true HEPA purifiers:

  • “HEPA-type” filters are not standardized and cannot match the performance of true HEPA purifiers. Often they don’t disclose the minimum particle size they can work well for. This means they’re not a good choice generally.
  • True HEPA purifiers are verified to meet demonstrated performance. They’re standardized and must meet the 99.9% efficiency / 0.3uM particle size quality standard.

When shopping, keep this in mind. It’s worth spending a little bit more for a better purifier that can permanently remove microscopic particulates that trigger allergies, coughing, and even sickness.

I’ve got a great list of some of the best true HEPA purifiers you can buy today here.

Additionally, the GermGuardian AC4825 that I mentioned is a great choice – I even own one myself! Here’s my comprehensive review of one of the most popular purifiers sold today.

Your comments are welcome!

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