Alen BreatheSmart Flex vs 45i – WiFi, red light, filter & comparison


Alen BreatheSmart weren’t just new Alen air purifiers. They were specifically designed to improve the quality of sleep. Alen partnered with SleepScore Labs, the Sleep Science Company that evaluates the effect of various devices on sleeping patterns. Which BreatheSmart Air purifier is worth buying – Alen BreatheSmart Flex vs 45i?

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  • BreatheSmart FLEX: great budget option if you want the Alen name, but not the high price tag; most affordable purifier compared and cleans up to 700 sf with a filter that lasts 6-9 months; lacks air quality detection, “pink noise frequency”, and the variable color options
  • BreatheSmart 45i: best for medium to large-sized spaces (up to 800 sf) with a shorter filter lifespan (only 6-9 months); moderately priced
  • BreatheSmart 75i: best for max area coverage (up to 1300 sf) and a long-lasting filter (up to 12-15 months); also the most expensive
  • BreatheSmart Classic: great balance of price, coverage, and filter life; cleans up to 1100 sf with a filter that lasts 8-9 months; price and specs fall between the 45i and the 75i
  • BreatheSmart FIT50: best for large areas (up to 900 sf) with a long-lasting filter (up to 10-12 months); price and specs fall between the 45i and the Classic


Everybody knows that the best products in the market are never cheap. iPhone is not the cheapest version, Yankee candles are not the cheapest, and the same is true for Alen BreatheSmart air purifiers.

The prices for the small units start at around $300-$400 and can reach almost $1,000 for the biggest 75i. If you consider that people usually buy 2-3 BreatheSmart air purifiers in one purchase, it can get quite expensive.

Which has higher coverage – Alen BreatheSmart Flex vs 45i?

BreatheSmart 75iCoverage: 1300 sf.
Air Quality Sensor: Yes
Filter Life: 12-15 mo.
BreatheSmart 45iCoverage: 800 sf.
Air Quality Sensor: Yes
Filter Life: 6-9 mo.
BreatheSmart ClassicCoverage: 1100 sf.
Air Quality Sensor: Yes
Filter Life: 8-9 mo.
BreatheSmart FIT50Coverage: 900 sf.
Air Quality Sensor: Yes
Filter Life: 10-12 mo.
BreatheSmart FLEXCoverage: 700 sf.
Air Quality Sensor: No
Filter Life: 6-9 mo.

What are the differences – Alen BreatheSmart Flex vs 45i?

To save you countless hours of research, we’ve included an in-depth look at those differences in this Alen BreatheSmart review:

  • Room Size Coverage (The amount of space the air purifier can handle in square footage.)BreatheSmart Classic = 1,100 sq. ft.BreatheSmart FLEX = 700 sq. ft.BreatheSmart FIT50 = 900 sq. ft.BreatheSmart 45i = 800 sq. ft.BreatheSmart 75i = 1,300 sq. ft.
  • Timer Function (Automatically turns the unit off after a specified time.)BreatheSmart Classic offers 4, 8 and 12-hour timers.All other models offer 2, 4 and 12-hour timers.
  • Ionizer Function (This boosts the air cleaning power by electrostatically charging air molecules.)BreatheSmart FLEX is the only model without this feature.
  • Child Lock (Locks the control panel so the settings can’t be changed.)BreatheSmart Classic is the only model without this feature.
  • Pink Noise (The fan sound is tuned to generate a soothing frequency that can help you sleep better.)Only the 45i and 75i models include this feature.

Are there any similarities?

Regardless of the air purifier you choose, you’ll enjoy these benefits:

  • Customizable HEPA Filter (Traps 99.97% of pollutants down to 0.3 microns in size.)
    • HEPA-Pure – This is the basic version of the filter that removes indoor allergen particles, such as dust, pollen, pet dander, and mold spores.
    • HEPA-Silver – This version includes an antimicrobial compound on the HEPA material that protects it from bacteria and microbe growth. An additional layer of Activated Carbon also reduces light odors and chemical compounds in the air.
    • HEPA-OdorCell – This version features hundreds of cells filled with Alen’s patented Molecular Conversion Powder in addition to the HEPA material. Odors from pets, babies, and cooking are destroyed at a molecular level to leave the air smelling fresh.
    • HEPA-FreshPlus – This version includes 3 lbs. of Activated Carbon in addition to the HEPA material. It provides maximum performance against household odors and chemical vapors from cleaning products, smoke, cooking, pets, etc.
  • Smart Sensors – These sensors monitor the air quality and automatically adjust the device’s fan speed to filter out pollutants. Consider it intuitive intelligence that works on your behalf.
  • Timer – This allows you to set up a time in the future for the device to shut off. The timer function ranges between 2 to 12 hours. (See the differences section below for specifics on each BreatheSmart machine).
  • Numerous Color Options – More than 14 different colors and designs available so you can match your personal style and taste. Also includes unique options such as brushed bronze, marble, rosewood, and more.
  • Forever Guarantee – Your air purifier is covered forever. If anything goes wrong with the internal components, Alen will replace the machine free of charge. (Filters are not included.)

Alen BreatheSmart Flex vs 45i reviews


Alen BreatheSmart FLEX

Right off the bat, you’re going to notice that the Alen BreatheSmart FLEX has a simple design that is quite pretty. It’s minimalist, and it comes in fourteen different color patterns. Because of this, you can put it anywhere you want, and it will match whatever decor or interior design you have.

Alen BreatheSmart 45i

One of the first things that you will notice is the design of this air purifier. It’s sleek, to put it mildly. And since it comes in 14 different colors, you’ll be able to choose the color that you most prefer. Each color goes very well with the sleek and minimalist design of the air purifier.

BreatheSmart FLEX vs. FIT50 vs. 75i


Alen BreatheSmart FLEX only weighs 15 pounds, as well, and there is a small handle on the top of the air purifier. This makes it easy to pick it up and move it around, to different parts of your home.

You can put the Alen BreatheSmart 45i just about anywhere, and it won’t take up too much space. Due to its sleek and minimal design – combined with the relatively lightweight nature of the purifier; it weighs just less than 24-pounds.

Room coverage

Using the Alen BreatheSmart FLEX, you can purify a room that is up to 700 square feet. For most Air Purifiers, this is quite good, and because of it, you can easily purify your living room, or even your entire apartment, if you live in a studio.

You can use this Alen BreatheSmart 45i in rooms and spaces that are, at most, 800 square feet. Now, you could use this air purifier for spaces that are larger, but it definitely isn’t recommended. Using it in a bigger space will result in less actual air purification being done.

The actual air purification process is efficient because the entirety of that 700 square feet space is cleaned every 30 minutes. And this is done using a HEPA-Silver filter.

Alen BreatheSmart 45i


Alen BreatheSmart FLEX

Now, the most notable feature of all is easily the HEPA-Silver filter that this air purifier offers. This filter has been designed to take care of allergens, mold, bacteria, dust, and even fungi, as well as various odors.

The filter does this through the use of a compound that has been designed with antimicrobial properties. What this compound does is it takes in the fungi and bacteria that the purifier is sucking in, and it inhibits their growth.

With the odors, the filter has an odor eliminating carbon built into it, and this carbon absorbs the particles that comprise those odors. Based off of the information that Alen has provided, the odors from cooking, as well as chemicals, especially from cleaning, are absorbed the best. Other odors are absorbed as well. But paint fumes have, according to many people, been a bit of a challenge.

Alen BreatheSmart 45i Review

Now, before we get into the flaws of this air purifier, there is one last thing that must be mentioned. Each one of the purifiers that Alen manufactures comes with the Alen Forever Guarantee. This is a lifetime warranty, which means that if you ever have any problems with the purifier, you can send it to them, and they will either fix the problem or give you a new one.

As for the flaws, there is only one flaw. And that’s the fact that the air purifier doesn’t work with spaces larger than 800 square feet. However, this is not a direct flaw, more of a design choice, and as such, it won’t affect you. Unless, of course, you intend to use it in a room/space larger than 800 square feet. Have a look at the larger Alen BreatheSmart 75i Air Purifier.

Alen BreatheSmart 45i

Now, this HEPA-Silver filter consists of four individual stages. The first is that of a Pre-Filter that captures larger particles and debris, such as pet hair. Then, the second stage is the Silver Filter, which captures and then eradicates things like mold, fungus, and other nasty substances.

The third filtration stage consists of a HEPA-Pure filter which filters out all of the allergens. Finally, the fourth filtration stage is a Carbon Filter, which gets rid of any nasty stenches or odors that may be lurking around in your space.

While all of this is going on, the air purifier is quiet. That’s because it uses WhisperMax technology. Even on the highest fan speed – there are four to choose from, based on your specific air purification needs – it is still quiet, and you can sleep with the air purifier on.

Other common features

Now, Alen has taken the time to integrate WhisperMax technology into this air purifier, as well. This serves a very notable purpose because if you have a small apartment or are using this air purifier in a bedroom, too much noise can be rather annoying. With WhisperMax technology, significantly less noise is being produced, in comparison to other Air Purifiers, and this makes the experience less intrusive.

Using a laser-smart sensor, the Alen BreatheSmart can detect particles in your air that are as small as 0.3 microns. And then, these sensors feed this data into the main unit, which begins to adjust itself to accommodate the purification that must be done.

There is a small LED screen that is on this air purifier. To see your air quality, along with some other information, you can just glance at it.

Alen BreatheSmart Flex vs 45i comparison chart

Alen Air Purifier:BreatheSmart 75iBreatheSmart ClassicBreatheSmart 45iBreatheSmart FLEXBreatheSmart FIT50
Max. Coverage Area:1,300 square feet1,100 square feet800 square feet700 square feet900 square feet
CADR Rating:350300245225220
Max. Airflow:347 CFM290 CFM215 CFM187 CFM231 CFM
Power Output:1.8 – 45 Watts1.6 – 105 Watts1.1 – 50 Watts0.8 – 45 Watts1.2 – 60 Watts
Filters:75i True HEPA (H13)True HEPA Pure (H13)45i True HEPA (H13)True HEPA Pure (H13)True HEPA Pure (H13)
Filter Lifespan:Filter Price:12 Months$$$$12 Months$$$$12 Months$$$$12 Months$$$$12 Months$$$$
Noise Levels:25-49 dB42-56 dB23-49 dB39-55 dB32-49 dB
Air Purifier Price:$$$$$$$$$$$$$$$$$$$$$

Alternate of Alen BreatheSmart Flex vs 45i 

Alen BreatheSmart 75i


  • Most energy-efficient air purifier
  • Quietest air purifier with 25-49 noise level internal; perfect for bedrooms
  • True air purification powerhouse; with 350 CADR rating
  • It can cover 1,300 sq ft – that means you can use it to purify the air in more than 1 room
  • Incredibly energy-efficient and quiet operation


  • It’s definitely pricy because you can buy 1 unit to cover several rooms
Max. Coverage Area:1300 sq ft
CADR Rating:350
Max. Airflow:347 CFM
Filters:75i HEPA Pure
Filter Lifespan:12 Months
Power Output:0.8 – 45 Watts
Noise Levels:25-49 dB
Dimensions:27″ x 18.5″ x 11.5″
(H x W x D)
Weight:27 lbs

Words hardly describe how well-balanced Alen BreatheSmart 75i. This is the perfectly engineered air purifier everybody is talking about. It is rated as the #1 air purifier in 2021 overall, based on the analysis of 529 AHAM certified air conditioners.

The 75i model is an upgrade of the very popular Classic model from the 1st BreatheSmart series.

It’s quite incredible that a low-wattage Energy Star certified air purifier can produce such air purification CADR rating. It’s the ultimate eco-friendly air purifier.

On top of that, it’s the quietest air purifier ever design. At a low fan speed setting, it produces merely 25 dB.

The 75i model solves both issues many air purifiers struggle with the most:

  • It’s extremely energy-efficient. An eco-friendly 45W max engine powers it.
  • The 75i is the quietest large room air conditioner with up to only 49 dB noise levels.

Now, both of these specs are brilliant.

But it gets even better:

75i outmatches all BreatheSmart model in capacity. Get this: it has a CADR rating of 350. All other units have a CADR rating of 200ish, or 300 (Classic model). With such a high CADR rating, 75i is more than capable of covering 1,300 sq ft; that’s almost unheard of. As such, the 75i model is considered to be the best air purifier for large 1000+ sq ft rooms,

All in all, 75i BreatheSmart is an engineering masterpiece. Add the brilliant True HEPA filters, which are the basis of the BreatheSmart air purifiers, and you have yourself the best large room air purifier.

Editor’s recommendations

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