In this Alen BreatheSmart FLEX vs 45i review, we will compare two of the most popular devices by the Austin, Texas-based company known for its high quality air purifiers.
Both models can be personalized not only in terms of filter capabilities, but also when it comes to the colour of the front panel. Both are backed by an unlimited warranty. So should you opt for the entry-level BreatheSmart FLEX, or invest in the newer BreatheSmart 45i?
This side-by-side comparison will help you find out.
Alen BreatheSmart FLEX
Alen BreatheSmart 45i
Coverage Area
Up to 700 ft²
Up to 800 ft²
CADR (Particles)
225 m³/h
245 m³/h
Power Consumption
0.8 – 50 Watts
1.1 – 50 Watts
Working Noise
25 – 50 dB(A)
23 – 49 dB(A)
PM 2.5 Sensor
No
Yes
Comparison: Alen BreatheSmart FLEX vs 45i – What are the Differences?
Coverage Area
Alen recommends the BreatheSmart FLEX for rooms with a surface area of up to 700 ft² (65 m²), while the slightly more powerful 45i is suitable for up to 800 ft² (74 m²). In both cases, the numbers were based on an assumed two air changes per hour (ACH).
Winner: BreatheSmart 45i
Up to 700 ft²
Up to 800 ft²
Clean Air Delivery Rate
Equipped with a True HEPA 13 filter, the BreatheSmart FLEX and 45i remove 99.9% of particles greater than 0.1 microns. Alen even allows you to pick a filter configuration depending on your exact needs, for example, one especially effective against pet odours or one against smoke.
The FLEX variant goes through a maximum of 187 cubic feet per minute (CFM), resulting in a Clean Air Delivery Rate (CADR) of 225 m³/h. Meanwhile, the 45i purifies up to 215 CFM and has a slightly higher CADR of 245 m³/h.
Winner: BreatheSmart 45i
225 m³/h
245 m³/h
Working Noise
Running at full speed, the BreatheSmart FLEX operates at around 50 decibels (dB). On the lowest speed setting, it generates 25 dB of noise. Hence, despite being the more powerful model of the two, the 45i does have a slight edge in both cases.
The FLEX and the 45i both come with four different speeds. But unlike its predecessor, the 45i can also be set to automatic mode. It will then only run as fast as needed to keep air pollution levels down, thereby preventing unnecessary noise and energy usage.
Winner: BreatheSmart 45i
25 – 50 dB(A)
23 – 49 dB(A)
Sensors & Display
Laser sensors provide the BreatheSmart 45i with the current temperature, humidity, and amount of airborne particles inside the room. Changes are detected almost in real-time and can be used as input for the automatic mode (see above).
The 45i also allows you to view this information as well as the air quality history via an app on your smartphone (see below), something that is not possible with the FLEX. LED colour rings on the display of both devices make it easy to check the current air quality at a quick glance.
Winner: BreatheSmart 45i
No / LED
Yes / LED
Connectivity & Compatibility
Using a Wi-Fi connection, you can monitor and control the BreatheSmart 45i remotely using the Alen Air app on your smartphone. However, it can not be integrated with a smart voice assistant. The FLEX model is not equipped with any connectivity capabilities.
Winner: BreatheSmart 45i
No
Yes
Weight & Dimensions
In the final round of this Alen BreatheSmart FLEX vs 45i comparison, we will have a quick look at the weight and dimensions of the two devices. Despite the added features, the 45i weighs exactly the same as the FLEX and also comes in the same size as its predecessor.
Winner: Draw
25 x 15 x 8.5 in, 15 lbs
25 x 15 x 8.5 in, 15 lbs
Conclusion: Alen BreatheSmart FLEX vs 45i – Which is the Better Air Purifier?
Being the entry-level model, the Alen BreatheSmart FLEX unsurprisingly finishes second in this comparison against its newer and more expensive successor. That said, it does offer a comparable coverage area, CADR and almost equally low noise level at an attractive price.
The better choice overall, however, is the Alen BreatheSmart 45i. Not only is it more powerful, but also equipped with more features such as automatic mode or the ability to control it remotely. At the same time, Alen managed to make the newer model even more quiet while not adding any extra weight or size.
Alen BreatheSmart FLEX
Alen BreatheSmart 45i
Looking for an even more powerful smart air purifier? Find out how the 45i performs against its successor in our comparison Alen BreatheSmart 45i vs 75i. For a non-connected alternative, read our comparison Alen BreatheSmart 45i vs FIT50.