Alen 45i Air Purifier Review – Is It Worth The Cost?

Josh Mitchell

Written By

Josh Mitchell

Expert Reviewed By

Holly Curell

Last Updated On

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Having kids, pets, and a husband prone to allergies means that I am always searching to improve my indoor air quality and keep my living space fresh.

Over the years, I’ve had the opportunity to test many of the best air purifiers on the market, and let me just say that as technology improves, so does air quality and easy breathing!

For the last three months, I’ve been challenging the Alen 45i to clean the air in the my bedroom.

In this comprehensive Alen 45i air purifier review, I’ll explore the features, performance, and design of this outstanding air purifier.

To fully test the air purifying performance of the Alen 45i Air Purifier, I took this product out of the lab and right to where it matters the most – my home.

This allowed me to use the product in all of my real-life scenarios: kids, pets, cooking odors, cleaning chemical odors, and more.

For 90 days, I have looked at many factors. My Alen BreatheSmart 45i review looks at all of the following:

  • Use of True HEPA air filter
  • Assessing energy consumption
  • Noise output
  • Fan speed
  • Pet odor elimination
  • Sleep quality
  • Energy consumption

We aim to provide you with an in-depth understanding of this top-of-the-line air purifier, helping you make an informed decision on whether the Alen 45i is the right choice for your needs.

Alen 45i Air Purifier Review


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Who is the Alen 45i Air Purifier best for?

The Alen 45i BreatheSmart air purifier is designed to purify medium-sized spaces up to 800 square feet, making it an excellent option for living rooms, bedrooms, or offices.

I was excited when it arrived just as I was making dinner (ie, filling my home with wonderful smoky smells) because I knew this would be an excellent first test.

Set-up only took a couple of minutes, with the bulk of the work taking the plastic off from the medical grade filters and popping them in.

As I turned the unit on, it immediately lit up with a bright blue light, and over the course of about 90 seconds, I saw it cycle through green, yellow, and red, and finally land on purple.

A quick glance at the user manual told me that purple is the worst air quality indicator.

This was great news (for my testing… obviously not my breathing!)

I set the unit to “Auto Mode,” which automatically changes the fan setting to adjust to the current air quality.

After two hours running at the highest setting, the air in my open floorplan of kitchen, dining, and living room was clean and showing a blue light again.

Alen 45i Air Purifier - Placed in Living Room

The Alen 45i comes equipped with advanced features such as app connectivity, real-time air quality monitoring, and multiple filter options, guaranteeing you'll enjoy clean, fresh air in your living space.

I really appreciate that it’s truly designed to run 24/7. Its sleek design will blend into any modern space, and it’ll quickly become your everyday air cleaning buddy.

I initially looked into getting the Alen Air 75i, which is slightly larger and covers 1300 square feet, but overall I’m glad I went with the 45i.

At only 15 pounds, it’s easy enough to move it to where I need it most.

I’m already considering buying two more because I think it would be more suitable to have smaller devices at all of my high traffic areas, rather than one larger unit.

My only complaint about the Alen BreatheSmart 45i Air Purifier is that on Turbo mode, it is quite loud. I measured 58 dB right next to the unit.

I will say that at a medium setting, I was only getting 40 dB, which is quieter than most fans and other air purifiers.

Overall, this is a great air purifier for pet owners and anyone who appreciates breathing easy within their home.

At just over $400, it’s priced right for the powerful unit that it is.

TL;DR: Alen 45i is one of the most powerful and popular air purifiers costing a reasonable amount and with the capacity to cover 800 sq.ft. The lifetime warranty is a testament to its durability and built quality.

The Highlights And Shortcomings Of The 45i BreatheSmart

  • Powerful and stylish option for spaces up to 800 square feet
  • Advanced features with app connectivity and real-time air quality monitoring
  • Color changing lights tell you the current air quality
  • Lightweight model with easy carrying handles
  • True HEPA Filters with options for add-on filters
  • Lifetime warranty with registration
  • Filter replacement costs are a bit costly
  • Turbo mode (highest speed) is noisy at 69 dB

Complete Specs For The Alen 45i



CFM (Cubic Feet Per Minute)

Speed 1: 70 CFM
Speed 2: 135 CFM
Speed 3: 175 CFM
Turbo Mode: 215 CFM

CADR (Clean Air Delivery Rate)



800 Square Feet


25” x 15” x 8.5”

Energy Star Rating


Filter Options

Various: HEPA, odors, VOCS, smoke, carbon, etc

Filter Life

12 months

Real Time Air Quality Monitor


Wi-Fi Connectivity



“Forever Guarantee” Lifetime Warranty with registration

Related Article: What is CADR Rating?

Premium Design And Aesthetics

The Alen 45i BreatheSmart air purifier is not only a powerful air purifier but also an aesthetically pleasing addition to your home.

Your purchase comes with your choice of 6 different designer panels:

  • White
  • Oak
  • Weathered Gray
  • Brushed Stainless
  • Graphite
  • Espresso

These panels are interchangeable if you decide to change up your room’s look. However, that comes at a cost, with each additional panel priced at $59.

This didn’t really seem reasonable to me (it’s just a plastic faceplate), so I decided to stick with the classic white color.

The device employs a bottom-to-top airflow system and measures 15 inches in width, 8.5 inches in depth, and 25 inches in height, making it a versatile choice that can fit seamlessly into any room.

TL;DR: Alen 45i offers premium design with interchangeable face plates to match your interior design.

Key Features Explained

The Alen 45i BreatheSmart air purifier is packed with useful features to enhance your air purification experience.

It offers an auto mode that adjusts the fan setting based on real-time air quality monitoring.

While it’s a nice setting, I have found that sometimes when I’m doing something that will stir up a bit of pollution (like cleaning or vacuuming) that it will switch between features pretty rapidly back and forth, which almost seems taxing on the motor.

For this reason, I pretty much keep mine at the “Speed 2” setting at all times.

The Alen 45i also provides multiple light settings, ensuring you can customize your air purifier to suit your needs and see your current air quality with just a glance.

I was amazed that when the Canadian wildfires were blowing smoke over the US, that the sensors picked it up pretty much in sync as they were telling us on the news!

Alen 45i Air Purifier - Light Settings

What Makes The Alen 45i A Smart Air Purifier?

The Alen 45i BreatheSmart air purifier is a smart air purifier because it uses internal air quality sensors to show you your current air quality in real-time.

Additionally, it is Wi-Fi compatible, which means you can check out your air quality and adjust settings from anywhere on the globe through your smartphone.

Internal Air Quality Sensors And Light Indicators

Alen 45i Air Purifier - Placed in Kitchen

The Alen 45i Air Purifier is equipped with a particle air sensor and multiple light settings, allowing you to keep track of your indoor air quality.

The particle air sensor detects allergens and other airborne particles in the air, while the various light settings provide a visual indication of the air quality in your room.
  • Blue (cleanest air)
  • Green
  • Yellow
  • Red
  • Purple (worse quality air)

With these features, you can easily monitor and adjust your air purifier's performance to ensure optimal air quality at all times.

Since I’m running the device 24 hours per date with the HEPA filter, I have found that it will always stay at a constant blue now, unless I’m doing something like cooking.

TL;DR: Alen 45i has an internal particle sensor with easy to identify light indicators for varying air quality levels. Blue being the cleanest, purple being the worst.

Robust App Connectivity

The Alen 45i Air Purifier offers app connectivity through the Alen Air App, allowing you to monitor and control your air purifier from the palm of your hand.

With this feature, you can remotely adjust fan speeds, change filter settings, and receive notifications about your air purifier's performance.

This will ensure you always have access to clean, fresh air in your living space.

I was able to connect to the app very quickly and my favorite feature is that you can manage multiple Alen devices from the app, and even name their location.

The app monitors both air quality and filter life, and even gives you local outdoor weather updates to help you better understand your air quality.

These features are above and beyond the features of other air purifier apps.

I also found the app more intuitive to use than other top brands, like the Dyson Link App.

Alen 45i Air Purifier - App Connectivity

TL;DR: Alen 45i has one of the most robust app allowing you to control, monitor and interface multiple Alen devices at once.

Alen 45i Filter Options And Performance

When you order your Alen 45i, you have the option to customize your air filters based on the needs of your home, which I’ll cover in just a moment.

You also have the option of starting a subscription to receive a replacement filter at intervals of your choice of 6, 9, or 12 months.

While a subscription is not mandatory, Alen does give you a 10% discount on filters with an active filter subscription.

True HEPA Filter

All of the filter options for the Alen 45i are True HEPA filters.

The True HEPA filter is a key component of the Alen 45i HEPA Air Purifier, capable of capturing 99.99% of airborne contaminants down to 0.1 microns.

This high-performance medical grade HEPA filter is ideal for removing allergens, dust, and other airborne particles from your indoor air, providing a cleaner and healthier living environment for you and your loved ones.

With the increasing popularity of HEPA air purifiers, the Alen 45i stands out as a top choice for maintaining clean air in your home.

The filter is designed to last 12 months and is easy to replace when needed.

The filter is also certified by the Association of Home Appliance Manufacturers (AHAM) for its superior performance.

Alen 45i Air Purifier - Filter Replacement

TL;DR: The true HEPA filters as features in this model can eliminate particles and microbes as small as 0.1 microns.

Filter Options Available
  • Pure Filter
  • Fresh! Filter
  • Odor Filter
  • VOC / Smoke Filter

The basic filter is $69 to replace, while each filter following it has a bit more oomph to help you really clean your air.

The strongest filter, the VOC / Smoke Filter, is $120 to replace. Compared to other brands like TOSOT, the Alen Air brand has filters that are readily available online.

I find that the increased price is worth the peace of mind.

TL;DR: You have the option to choose more powerful filters at a price. The most powerful filter is capable of removing VOCs.

Activated Carbon Filter

how do air purifiers work

The Activated Carbon filter in the Alen 45i Air Purifier is designed to absorb smoke, odors, and chemicals from the air, effectively reducing these common household pollutants.

With 2+ lbs of activated carbon, this filter is highly effective in neutralizing unpleasant odors and improving your overall indoor air quality.

TL;DR: The activated carbon filter is great at removing smells and odors.

HEPA-Silver Filter

The Alen 45i Air Purifier also features a HEPA-Silver filter, which utilizes medical-grade HEPA 13 true filter with silver nano technology.

This advanced filter effectively eliminates viruses and bacteria from the air, providing an additional layer of protection for your household.

HEPA OdorCell Filtration

The Alen 45i BreatheSmart air purifier is also equipped with HEPA OdorCell filtration technology.

This advanced filtration system combines a True HEPA filter with an activated carbon filter to effectively eliminate odors, allergens, and other airborne particles from the air.

With this powerful combination, you can enjoy clean, fresh air in your living space.

I have found the Alen 45i to be fantastic at controlling dust particles, airborne allergens, and pet dander throughout my home.

Ionic Feature

The optional ionizer in the Alen BreatheSmart 45i air purifier adds an extra layer of air purification by emitting negative ions into the air.

These ions attach to airborne particles and pollutants, increasing their weight and making it easier for the air purifier's filter to capture them.

This Ionic feature can be easily turned on or off, depending on your preferences.

I’m still a bit weary of using ionizers in the home, especially since my husband has asthma. The research is still so-so on the benefits of this feature.[1]

what is an ionizer

TL;DR: You can opt for an optional ionizer feature which can further help remove particles using negative ions

Related Article: What is an Ionizer?

Room Coverage And Noise Levels

Alen 45i Air Purifier - Noise Level

The Alen 45i BreatheSmart air purifier is designed to provide optimal coverage and performance in medium-sized spaces up to 800 square feet.

With a noise level range listed of 23-49 dB, the Alen 45i operates quietly, making it suitable for use in living rooms, bedrooms, or offices without disturbing your peace and quiet.

My own testing had a slightly higher range, with 35 dB at the lowest setting and 58 dB at the highest setting.

The highest setting is admittedly a bit too loud for sleep for most, but I would compare it to that of your average window air conditioner.

If you enjoy sleeping with a fan on like I do, you may even find the lowest fan setting to be too quiet. In fact, its pink noise feature can even help improve your sleep quality!

TL;DR: Alen 45i is designed to cover spaces up to 800 square feet with noise levels ranging from 35 dB to 58 dB.

Energy Efficiency And Operating Costs

The Alen 45i BreatheSmart air purifier is not only a powerful air purifier but also an energy-efficient one.

With a power consumption ranging from 1 to 50 watts, depending on the setting, the Alen 45i is designed to minimize energy use and keep your utility bills in check.

In this section, we'll discuss the initial buying costs, power consumption, and filter replacement costs of the Alen 45i air purifier.

Initial Buying Costs Is High But Worth It

The initial buying cost of the Alen 45i BreatheSmart air purifier is $429.

While this price may seem steep, it's important to consider the long-term benefits of investing in a high-quality air purifier.

With its advanced filtration technology, energy-efficient operation, and lifetime warranty, the Alen 45i is a worthwhile investment for those seeking to improve their indoor air quality and overall health.

TL;DR: Alen 45i has a high up front cost but it is worth the quality. From filtration technology to lifetime warranty, this unit is synonymous with quality and durability. 

Power Consumption - Quite Energy Efficient

The Alen 45i BreatheSmart air purifier consumes between 1 and 50 watts of power, depending on the setting.

This energy-efficient operation ensures that you can enjoy clean, fresh air without worrying about skyrocketing utility bills.

In fact, the estimated electricity cost for running the Alen 45i air purifier is approximately $4.38 per month, making it an affordable option for maintaining a healthy living environment.

It’s also Energy Star Rated, which if you’re watching your power consumption, should always be your first priority.

The 45i’s big brother, the Alen Air 75i, even made the Energy Star list of most efficient room cleaners of 2023.[2]

TL;DR: Alen 45i is energy efficient and energy star rated. It consumes between 1 to 50 watts depending upon whether it is idle or running at turbo speed.

Replacement Filters Cost Is Generally High But Necessary

While the Alen 45i BreatheSmart air purifier offers exceptional performance and energy efficiency, it's essential to consider the filter replacement costs.

The cost of filter replacement for the Alen 45i air purifier ranges from $69 to $119, depending on the specific filter type.

While these costs can add up over time, it's important to remember that regular filter replacement is crucial for maintaining optimal air purification performance and protecting your health.

I have been happy with the basic “Pure” filter so far. Unless you’re facing wildfires or other strong pollutants, I wouldn’t feel a huge need to upgrade beyond this.

TL;DR: The filter replacement cost is unfortunately quite expensive for this unit.

Customer Service And Warranty

Alen Corporation is committed to providing exceptional customer service and a lifetime warranty on their products, ensuring that you can enjoy the benefits of your Alen air purifier, the Alen 45i BreatheSmart, for years to come.

Customer Support

Alen Corporation provides outstanding customer support for the 45i Air Purifier, offering assistance via phone, email, and live chat.

I haven’t had to contact them myself yet, but from the many reviews I’ve read, I have gathered that their customer service team is knowledgeable and responsive, ensuring that you receive the help you need when you need it.

Lifetime Warranty

The Alen 45i BreatheSmart air purifier comes with a lifetime warranty when you have an active filter subscription, providing you with peace of mind and protection for your investment.[3]

This warranty covers any defects in materials or workmanship, as well as any issues with the air purifier's performance.

To make a warranty claim, simply contact Alen Corporation directly, and they will provide further instructions on the steps to take.


If you purchased your Alen 45i prior to 2022, you do not have to have a filter subscription to claim your lifetime warranty.

Alen 45i Air Purifier - Guide & Warranty

TL;DR: While the lifetime warranty is an exceptional offering, the quality of customer service is equally phenomenal. 

Comparing Alen 45i To Other Alen Models

Alen BreatheSmart 45i Vs Alen BreatheSmart75i

You can think of the 45i as the “little brother” of the Alen BreatheSmart75i, especially in terms of size and power.

The style, design, and air filtration system are all the same, with the 75i coming in 2” bigger in height, width, and depth.

The 45i is 14 pounds and suitable for areas of up to 800 square feet, while the 75i is 27 pounds and can handle up to 1300 square feet.

For this reason, naturally the 75i is more expensive (by about $250) and its filters are more costly as well.

Since I was focused on purifying my bedroom, the 45i was the best air purifier for my needs.

However, the 75i would be awesome for my open floorplan downstairs, so it’s something I’m definitely considering!

TL;DR: Alen BreatheSmart 75i is the more powerful version of the 45i in the sense that it covers a larger area. The features are more or less the same.

Alen BreatheSmart 45i Vs Alen BreatheSmart FLEX

The BreatheSmart Flex was the original model of the BreathSmart series from Alen, and although there are still some models for sale (often deeply discounted), it has been replaced with the Alen BreathSmart 45i.

The two models are identical in size and use the same filters.

The main differences between the FLEX and its upgrade (the 45i) is that the FLEX only cleans 700 square feet of air at 187 CFM, while the 45i cleans 800 square feet at 215 CFM.

Despite its stronger power, the 45i is also considerably quieter than the FLEX.

However, if you’re looking for an air purifier for a guest room or room that doesn’t get used very often, go for the FLEX if you can find it.

The discount alone will be worth it, and you’ll still be able to use the 45i filters for the unit later on.

TL;DR: BreatheSmart FLEX is an older model which has mostly been discontinued. It covers a smaller area but can be found at a cheaper price tag as compared to Alen 45i.


How Long Do Alen Air Purifier Filters Last?

For optimal performance, Alen air purifier filters typically last 6-12 months when the device is used 24 hours a day. This is slightly better than with most other air purifier brands.

Where Are Alen Purifiers Made?

len BreatheSmart air purifiers are designed in the United States and made in China.

Why Is My Alen Air Purifier Always Red?

The color red on an Alen Air 45i indicates poor air quality. Try turning the fan speed to Turbo to boost the purifier’s performance.

If this does not help within an hour, then you likely need a replacement filter.

How Long Has Alen Air Purifier Been Around?

Alen, an Austin-based air purifier company, has been providing customers with clean air since 2005. With their commitment to quality and exclusive Forever Guarantee, Alen is dedicated to helping people breathe better and live better.

What Is The Coverage Area Of The Alen 45i Air Purifier?

The Alen 45i air purifier is designed to effectively clean the air in medium-sized spaces of up to 800 square feet.

Overall ACLAB Grade - Our Verdict: A-

After our thorough evaluation, we've assigned the Alen 45i BreatheSmart air purifier an overall ACLAB grade of A-. 

The Alen 45i excels in performance, design, and features, providing an exceptional air purification experience.

However, the high filter replacement costs are a noteworthy drawback.

Overall, the Alen 45i is an excellent choice for those seeking a powerful, stylish, and feature-packed air purifier to improve their indoor air quality.

Alen 45i Air Purifier
Main Features

  • Powerful and stylish option for spaces up to 800 square feet
  • Advanced features with app connectivity and real-time air quality monitoring
  • Color changing lights tell you the current air quality
  • Lightweight model with easy carrying handles
  • True HEPA Filters with options for add-on filters
  • Lifetime warranty with registration


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Josh Mitchell


Josh Mitchell
My name is Josh and I am obsessed with home appliances. From portable AC units to heaters and air purifiers, I enjoy testing, learning and using these devices to improve the air quality inside my family home.

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Midea U Shaped Window Air Conditioner

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