Airthereal AGH400 Air Purifier: Trusted Review & Specs

The Airthereal AGH400 is the successor of the glorious “Glory Day” Airthereal AGH550, which is the most reputable large-room air purifier from this brand. It is a new tower air purifier that once again aims to compete in a higher price range. Okay, time for our Airthereal AGH400 review.

Airthereal AGH400 ranks A- in our air purifier ranking list. We give the biggest and most thorough database of air purifier reviews in the world.

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Founded in 2018, Airthereal Airthereal is an American home air quality brand that has built its reputation on accessible HEPA air purifiers designed for mid-range to large-room use. The Airthereal AGH400 review will introduce the best air purifier of this brand in 2026.

Other Airthereal’s Air Purifier Reviews:

Airthereal AGH400 Price

After several years of standing at the edge of the pool and occasionally dipping its toes in, American air brand Airthereal has finally decided to jump into the cold lido that is the premium large-room pet purifier market. Perhaps it took those ‘no shortcuts’ signs too literally, because while the Airthereal AGH400 is very good, it hasn’t made enough of a splash to truly threaten its big-name rivals.

The Airthereal AGH400, as it’s officially called – excuse the full name, but if you’re new to the brand, the company calls it the Glory Days AGH400 Pet Air Purifier – marks an ascension from the budget Airthereal APH260 and Airthereal AEH300.

It’s now priced akin to the Levoit Core 300S and Blue Pure 511i Max, and shall be judged accordingly. I know, the Airthereal AGH400 is a big step-down from the previous Airthereal AGH550, which targets a much higher price range. But it is too difficult to compete, so Airthereal is trying again with a more acceptable price point.

One thing you should know, the Airthereal AGH400 was released in early 2025 in two variations. You can pick up the Airthereal AGH400 with an H13 HEPA and activated carbon filter, and that’ll cost you $129, or there’s a Pet version with an OdorShield+ pet odor filter, and that sells for $149.

Related post: Best air purifier 2026.

Airthereal AGH400 Design and Size

It’s been a while since I’ve used an Airthereal air purifier that felt quite as chunky as the Airthereal AGH400. Partly, this is down to the 15-pound heft, putting it in a weight class the same as the old Airthereal AGH550 – a bulky console air purifier. For a tower air purifier at this price point, it is generous of Airthereal to offer a full-size air purifier designed for large rooms.

Take a look at its competition, and by no mean I’m a compact-purifier evangelist, but at 11.8 inches wide, the Airthereal AGH400 is at the other end of the spectrum from the likes of the Levoit Core 300S. It’s 21.3 inches tall and 11.8 inches wide, so it’s big. The Airthereal AGH400 should be an air purifier that costs you $200.

Well, the Airthereal AGH400 has a cylindrical, industrial-looking body, with an open-grid air intake that is ostensibly see-through so you can see the outer pre-filter. The wide intake mesh wraps fully around the lower body, though the upper spoiler outlet grille is a narrower, separate piece; the systematic part of me appreciated how cleanly the two halves divided their airflow duty.

Airthereal uses a bottom-to-top airflow system, which is common in cylindrical designs. However, because the AQI display is located around the top control panel, you can’t see the actual PM2.5 readings unless you sit closer to the Airthereal AGH400 itself.

Related post: Best air purifier for bedroom.

Airthereal AGH400 Filters

Normally, we will check the quality and quantity of the air filters to decide its performance, as well as the air filter types being used. The Airthereal AGH400 will use a new 5-stage air cleaning system as below.

1. Pre-filter – First, we have a washable pre-filter to trap pet hair and large particles.
2. Precision pre-filter – The second pre-filter can trap smaller particles than the first.
3. True HEPA filter – With the True HEPA filter, this air purifier can capture 99.97% of as small as 0.3 microns allergens, virus particles, pollen, mold and fungi particles.
4. Activated Carbon filter – Deal with odors and smoke. The Pet-specific filter has an OdorShield+ technology, which adds zeolite for better odor removal.
5. Final mesh filter – The final protection, which doesn’t really help in filtration.

The air filtration system of the Airthereal AGH400 tells us why Airthereal can bring the product to $149 range, instead of $299 like the old Airthereal AGH550. It is still the H13 HEPA filter, but we have only a thin layer of carbon filter to do the heavy tasks. The filtration feels more like marketing than actual filtration capability.

However, it is still the standard H13 HEPA filter. And in the real-world test, the Airthereal AGH400 does a good job, slightly better than the console Airthereal APH320. We’re paying cheap for a large-room air purifier that can work well even in 200-sq-ft test.

The new filter for the Airthereal AGH400 isn’t expensive for the performance it delivers, costing only $59 per year. You can buy the pet-specific filter for $89, but I think sticking with the standard filter is more than enough.

Related post: Best air purifier for allergies.

Airthereal AGH400 Room Coverage

Airthereal doesn’t bring the Airthereal AGH400 for Energy Star or AHAM verification anymore, so you need private tests like Breathe Quality to see its actual performance. The Airthereal AGH400 is recommended for rooms up to 2,000 square feet by the manufacturer, but it’s only for 1 ACH.

The ACH of the Airthereal AGH400 is 4X. This ACH is for rooms up to 500 square feet.

The CADR of the Airthereal AGH400 is 250 cfm in general.

Related post: Best large room air purifier.

Airthereal AGH400 Sound

Noise-wise, Airthereal has never released a model without a sleep mode to my knowledge. Instead, you can use sleep mode of the Airthereal AGH400 at 24 decibels (dB) for overnight running, dial up through the fan speed settings via the touch panel, or, if the household is empty and noise isn’t an issue, run it at full speed (58 dB) which moves air just the same as any other air purifier in this category.

We can say that the Airthereal AGH400 is such a good air purifier for bedroom, as long as you run it with Auto mode.

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Airthereal AGH400 Power Consumption

One of our most FAQs is “Do air purifiers use a lot of energy?” In fact, air purifier must be used for a long time to be efficient. And power consumption is one important criteria to review if this air purifier is good or not.

At 42 watts, the Airthereal AGH400 doesn’t have such good energy efficiency like the Energy Star rated Airthereal AGH550 in the past, but it is decent enough.

If you run the Airthereal AGH400 for 8 hours per day, it would cost you $18.4 each year.

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Airthereal AGH400 Additional Features

When the Airthereal AGH400 launched, it shipped with Wi-Fi connectivity built in, but by the time I tested it, the AIR.ai app had already received several firmware updates. That’s the first of what Airthereal promises to be ongoing updates, building on the connected platform they’ve already set up across models like the Airthereal APH320.

Airthereal has equipped the Airthereal AGH400 with a sensor array that’s easy to remember: PM2.5 and VOC. One reads fine particulate matter down to 2.5 microns, and the other detects gaseous compounds and odors, together feeding the auto mode with more input than a single-sensor purifier can provide.

Finally, we have Child lock setting, a Sleep mode, and LED indicator for filter replacement.

Related posts:

1, Best air purifier for smoke.

2, Best air purifier for dust.

3, Best air purifier for mold.

Airthereal AGH400 Customer Service

Despite of being established only in 2017, the Airthereal has proved to be a big air purifier brand of the North America market. They provide you with loyalty programs, discounted promotions and campaigns over the year, so you will satisfy with their products.

For the customer service, the Airthereal provides excellent support online. You can either call them for a toll-free service, email them at support@airthereal.com or live chat with them. If you have any immediate questions, you can reach their FAQs page to search for an answer.

Airthereal also guarantees for your satisfaction, so they give you a full refund within 30 days of purchase for any Airthereal product. For shipping, they are generous with the Free Shipping policy for any 3-7 days standard shipping. However, if you need fast shipping, you need to pay for extra charge.

Finally, all Airthereal air purifiers come with 2-year warranty, plus 1 year for online warranty registration. That is great, provided that they just only sell the budget air purifiers.

Our verdict

The Airthereal AGH400 is excellent for its price range, but it is still an air purifier from a lesser-known brand, so you should carefully consider whether customer service is important to you.